Added CMakeListst.txt files.
Moved lib/FileReader to lib/backend/FileReader
Made includes relative
Added lib/CMakeListst.txt
EngineBackend: removed all SDL code (Display and input will be handled in the client's code)
IEngineBackend: removed every display related methods
Added simple test code of the engine (src/main.cpp)
added test shader and material + monkey.bin model