Fix divide-by-zero error in vector:normalize()
and vector:normalize_in_place()
Merge pull request #5 from am0d/master

Fixes divide-by-zero error in vector:normalize() and vector:normalize_inplace()
Code cleanup
Make normalisation in hump.vector-light consistent with hump.vector
brief(er) vector factory
Remove camera dependencies. Add pos + rotation getter.

hump.camera is not independent of hump.vector-light.
camera:pos() returns the camera position.
camera:rotation() returns the camera rotation.
timer.lua: Add do_for(). Remove Interpolator, Oscillator.
Return GS callback result (for love.quit(), etc)
Add camera:lookAt(x,y). Augment camera:rotation([phi]).
Issue 9: Add camera:zoom[To]()
Allow arbitraty gamestate callbacks
[Gamestate] Remove __index metamethod for new gamestates (world of pain)
Deprecate gamestate constructor
Rewrite class system
Update license header
Update readme
Remove ringbuffer.lua
Update README.md

Typo fixed
Merge pull request #12 from Yonaba/master

Small typo fix in the Readme
Fix gamestate:init() bug, and error on undefined callbacks