Add chat box for command feedback and future chatting. Update commands.

- Add a larger, readonly "chat box" above the text input to display
  results of commands, errors, and user chat. This box is scrollable
  with the mouse wheel.

- GiveBlockCommand updates inventory/item list so that changes appear
  even if the inventory is already open.

- Add convenience method item.get_item which looks up the actual item
  instance for a given block/item id.

- Simplify resizing by taking it out of Control and forget attempting
  to write an anchoring algorithm

- Make Control a pyglet EventDispatcher to follow event conventions

- Use ChunkFive Roman font
Merge branch 'master' into chat-box

Conflicts:
	controllers.py
	gui.py
	inventory.py
	items.py
Make TextWidget font name configurable

- Use Arial for chat boxes.

- Use G.FONT_DEFAULT by default.
Add a HelpCommand to print out help_text of all commands.
Merge branch 'master' of https://github.com/boskee/Minecraft
Revert "Updated carrot and potato height"

This reverts commit 5c99e94fd7b56344e980e9c41a783276dab2d536.

Conflicts:
	blocks.py
Merge branch 'master' of https://github.com/boskee/Minecraft
Merge branch 'master' of git://github.com/ronmurphy/Minecraft
Fixes aa2885f9e0e40f245bf621c0f61708e2162fc50d.
Another fix for aa2885f9e0e40f245bf621c0f61708e2162fc50d.
Merge remote-tracking branch 'boskee/master'

Conflicts:
	commands.py
	items.py
Hide text inputs from TakeScreenCapCommand, and echo the save path
Furnace changes
Furnace changes(2)
Sectors: Changed size from 8xINFx8 -> 8x8x8
This means you can build as high or low as you like, vertical travel is
equivalent to horizontal travel performance wise.

Also optimized world.change_sectors
Improves setup.py to allow pyglet compilation.
Adds a section concerning pyglet compilation for more readability.
Fixes screenshot URL.
Saving: Added Region Save Mode
A very scalable system. Sectors (8x8x8 blocks) are stored 4x4x4 in headerless
files, 2 bytes per block. Position data is not stored, but inferred based on
the byte offset within the file.

Whole regions (32x32x32 blocks) are read at once when world._show_sector asks.
Sectors can be written to individually, though without a dirty_sectors system,
it currently writes all sectors in memory to disk during a save.
Merge pull request #60 from Nebual/saving-region

Saving: Added Region Save Mode