Added repetition constructors
Fixed thread-safety

Fixed huge mistake in Clock code (Allocating a mutex everytime instead
of locking it)
HashDigest and StringStream class are no longer thread-safe (That was
stupid anyway)
Improved File class source code

Made use of smart pointers to be exception-safe
Made use of StringStream (again)
OpenGL class now uses CallOnExit class
Fixed UberShader leak
Disabled face culling on default material
Made .idb files ignored
Optimized Renderer (it no longer makes useless allocations)
Fixed ShaderStage::Destroy