Put typedef into laco's header

Didn't actually know this was possible, but this makes it easier to
interface with an opaque LacoState rather than needing 'struct LacoState'
everywhere.
Remove struct for the type LacoState
Add argument names for header files
Remove variable name documentation
Merge branch 'typedef/laco-state'
Add FindLuaJIT to find luajit more reliably
Add module path for LuaJIT in base CMakeLists.txt
Change to find_package for luajit
Change to single LUA_LIBRARY just for consistency
Merge branch 'cmake/find-luajit'
Version bump to 0.2.0

* Make LacoState opaque
* Changed laco_initLacoState to laco_newLacoState