FamiTracker bugs

Demo FTMs available at https://www.dropbox.com/sh/21r4tkwjaujm41o/ZJzv_wQpL8
~: confirmed in 0.4.3

Output
~ The Hxy effect, hardware sweep up, is inaccurate and stops at note A in some octave.
~ In N163 channels, the Vxx effect state is reset to V00 if any wave sequence is played.
~ Upward frequency modulation in the FDS chip is inaccurate.
- The arpeggio 000 does not reset the effect's internal cycle.
~ In VRC7, the 3xx effect does not change the octave register, causing abrupt frequency changes at sufficiently low octaves (3~4 below that of the initial note with 3xx).
~ In VRC7, the 4xy effect causes overflow or underflow of the frequency registers at sufficiently high depth and a Pxx fine pitch (e.g. C-4 P00 48F).
- The Xxx effect randomly resets the DPCM counter to 00 when there was a note to which Xxx applies then the note was deleted, and the operand is sufficiently small.
~ Qxy and Rxy on the noise channel move more semitones than they are assumed to.

NSF
- Out-of-range Bxx and Dxx effects cause corruption.
- When using a Qxy/Rxy effect to bend a note to any octave outside the valid range (0~7), the note becomes corrupted.
- The 4xy effect leads the frequency/period register to underflow at sufficiently low frequencies or periods depending on the expansion type.
- In VRC7 and N163, the 4xy effect leads the frequency register to overflow at sufficiently high frequencies.
- When there is a Dxx effect that skips to any row other than row 00, then this effect will repeat in every frame.
- In VRC7, the 1xx effect causes overflow of the frequency register, warping the pitch between extremes.
- When frequency modulation parameters in the FDS channel are overridden by effects Hxx/Ixx/Jxx, new notes do not reset them to zero unless a new instrument is used.
- The Gxx effect on the last row of any pattern prevents the same row from playing if the row delay exceeds the amount of ticks in that row.

Inconsistency
- Vibratos 40y and tremolos 70y reset the effects' internal phase to 00 where they simply halt cycle increment in FamiTracker.
- The 7xy effect never drops to volume 0 in FamiTracker (except VRC6 sawtooth), but it does so in every non-2A03 channel in exported NSFs. (cf. http://famitracker.com/forum/posts.php?id=4457#45772)
- The MSB in the Sxx effect is ineffective, meaning SC0 will be equal to S40 in exported NSFs, S88 to S08 etc.
- S7F/SFF do not work.
- Once a note is released, it can be released as many times as desired whenever there is a note release.

Format
- It is possible to select patterns beyond frame boundaries, allowing corrupted data to be pasted.
- FamiTracker is unable to open modules that, for internal channels, contain 128 volume sequences, 128 arpeggio sequences, 128 pitch sequences, 128 hi-pitch sequences, and 128 duty sequences.
- FamiTracker is unable to open modules that use more than 0x7FFF bytes for VRC6, N163 or S5B sequences.
- Text modules using the N163 chip always require 8 channels in song definitions even when the number of N163 channels is otherwise determined by N163CHANNELS.
- The text importer does not distinguish the expansion-specific forms of effects and always assumes the first types of:
   . Hxy (2A03), Hxx (FDS), Hxx (5B)
   . Ixy (2A03), Ixx (FDS), Ixx (5B)
   . Jxx (FDS), Jxx (5B)
- Copying pattern injects random bytes from the memory into the clipboard when certain columns in a channel were not copied.
- Deleting characters from the song information fields may cause leftover of text beyond the 0x00 delimiter.

Interface
- If the last frame is removed and then a new frame is inserted after the last frame (not via the frame editor), this new frame contains pattern 00 in all channels instead of the first unused patterns.
- While removing duplicate patterns, patterns are considered different even when there are different values on inaccessible/unavailable fields (e.g. effects with no command, volume in DPCM).
- When there is a selection in the frame editor, clicking the frame editor area loses focus and sends the cursor to the pattern editor.
- After opening a non-existent file in the recent files list, FamiTracker creates a new FTM as usual, but "ghost" instruments from the current FTM remain in the instrument list, and the previous FTM's name stays in the title bar.
- Stopping an FTM does not reset the auto portamento in VRC7 channels when there is a 3xx effect on the first row and the note on the first row had been changed to a lower octave.
- FamiTracker prompts the user whether to save the current FTM if there are invalid characters in the song information, and FamiTracker tries to replace them with valid placeholder ones (e.g. 0x8145 for Shift-JIS, 0x3F for most Western encodings).
- While playing a frequency-modulated FDS note, opening the FDS instrument editor disables the FM.
- Shift+Mouse wheel does not work properly when selecting across channels. Values of column types are not shifted when these columns are not selected in either the leftmost or rightmost channel. For example in http://puu.sh/2hchk/158f7091fc, the instrument column is not selected in Pulse 1, nor is the effect column fx2 in Pulse 2; therefore only the volume columns and effect column fx1 respond to shift+mouse wheel.
- Pattern selection is broken towards the right edge of the channels.
- Playing a song with the Xxx command in the DPCM channel and pausing the song messes up DPCM previewing in the instrument editor.
- Comments editor does not allow Ctrl+A.
- Pressing Ctrl+S to save the current FTM may reset the channel where the cursor points to.
- Ctrl+click on the frame editor does not work when the current playing frame contains a Dxx at the end.
- These actions are not recognized as changes to the FTM:
   . Modify the row/2nd highlights
   . Change the vibrato style
- These actions can be performed even when edit mode is disabled:
   . Select, cut, copy, paste, delete
   . Paste and overwrite, paste and mix
   . Transpose (keyboard), Interpolate, reverse, replace instrument
   . Expand selection, shrink selection
   . Transpose (Ctrl+Mouse wheel), shift values (Shift+Mouse wheel)
- Number keys do not change the current octave in the Modplug Tracker pattern edit style.
- Certain keys on a normal QWERTY keyboard will not work properly if not in Swedish keyboard mode:
   . Key -/_ is misplaced;
   . Keyboard ;/: is disabled;
   . Key [/{ and key ]/} are swapped.
- The repeat key works separately on the effect command and the effect operand.

Extra
- In multichip FTMs containing the FDS and any sound chip other than VRC7, the virtual keyboard in the FDS instrument editor does not work.
- In multichip FTMs, when it is defined that there be fewer than 8 N163 channels, and FDS or VRC7 is used, then FamiTracker changes these channels to make up for 8 N163 channels.