Perapera Chinese: “Current browser only” mode bugfix and use

Bug: When in "Current browser only" mode, I had to manually enable the extension for every tab. Disabling worked for all tabs at once though. It didn't seem like an intended behaviour and Rikaichan does it differently

Fix: http://pastebin.com/TuQQikDS
It's just a partially reversion to Rikaichan code. (bro.cperapera==null) could be elaborated into (bro.cperapera===null || bro.cperapera===undefined) if you still prefer to keep it strict

Useless condition: I have no idea why ((ppcConfig.enmode > 0) || (ppcConfig.enmode < 2)) is there. That's always true for any integer ppcConfig.enmode, and so has no effect. Rikaichan (hope I'm not annoying with this one) does have just (rcxConfig.enmode>0) in there