contribution guidelines

[Felecarpp]

Hey, thanks for maintaining this library.
I am writing a visibility function and its requires (alignment and intersection functions).
What game development utilities this repository accepts ? Is it better to add a new file with require("hump.vector") or to put all the visibility function in vector.lua ? Do you accept dependency to luaunit in the test suite ? What is the describe function in spec/timer_spec.lua ?