Changelog mechanical patch

Adds:
- a new craft station: "Engineering Workbench" to access the new crafts
- cogs: allows you to carry mechanical energy from one point to another.
  You can connect cogs with belts, you can use cogs of different sizes,
  so you can controle the gear reduction.
  Be careful not to make them turn too fast!
- handcrank: generate energy by the force of your arms.
- chicken wheel: generator of mechanical energy, allow you to produce
  energy without having to lift a finger.
- mechanical craft stations: uses mechanical energy to craft new items:
  - crusher: recycle some items
  - milling machine: transforms your wheat into flour
  - milk separator: produces cream from milk
- pipes conveyors: pipes that allows you to transport items. You can
  connect a pipe under a chest or a craft station to output items,
  or above to set an input.
- mechanical conveyors: allows you to defy gravity and to move items
  faster!

Changes:
- chests have changed internally to allow pipes connexions (and future
  additions with a new GUI/features...), so if you encouter a new problem
  warn us.
- chickens jump at different heights depending on their rarity


This patch is the first of a serie of updates relative to energy and
automation. It's only the core of the first energy tier (mechanical energy)
that can be used directly at the beginning of the game.
Next updates will introduces new machines based on mechanical systems,
and new game mechanics.
Two next tiers will come later: steam and electricity.