Improved LuaInstance class

Better handling of panic (showing the actual error)
Secured arrays with static assert
Added ArgCheck
Added ArgError
Added reference handling
Improved DumpStack method (Now printing the address of functions,
tables, threads)
Renamed Directory::SetDirectory to Directory::SetPath

Added Directory::GetPath
Fixed Lua parser

Removed support for short C++ comment (//) since Lua 5.3 is likely to
have a // operator for integer division
Disabled error exception during Renderer::EnsureStateUpdate
Re-added proxy textures and glTexStorage2D optimization for cubemaps
Skeleton class now notify modifications
Added fastpath for operator==(const String&, const String&)
Added static methods/getter/setter to LuaClasses
Added Scene::EnableBackground
Alphabetical commit
Fixed Graphics module build