Merge pull request #270 from fragmer/master

Simplified timing code (remove adjustment based on currentTimeMillis)
Fixed ClassicWorld format compliance in LevelSerialzier

The Metadata tag is required by ClassicWorld specs, even if empty.
Fixed a syntax error. Derp.
Merge pull request #271 from fragmer/patch-1

Fixed ClassicWorld format compliance in LevelSerialzier
Rendering code cleanup part 1: eliminating reuse of loop variables and naming unnamed variables.
Rendering code cleanup round 2: eliminating more variable reuse, and naming more vars.
Eliminated redundant "renderer.minecraft." dereferencing all over the rendering code.
Cleaned up the networking code a little bit (still a loooooooot of work left to do). Moved packet-handling code out of tick() into handlePacket()
Improved efficiency and error checking in SelectionCuboid CPE implementation. Switched from List<SelectionBoxData> to HashMap<Byte, SelectionBoxData>, added range checks on input, and a log warning when attempting to delete a non-existent selection (might help debugging).
Overhauled handlePacket(): fixed EnvSetColor not resetting color when requested; improved variable names / comments / logging; fixed negative message IDs coloring messages yellow when MessageTypes are supported; fixed invalid map data crashing client ungracefully on LevelFinalize packet; fixed dimensions and colors in SelectionCuboid not getting validated or clamped.
Merge branch 'master' of github.com:fragmer/ClassiCube-Client