Adding unit tests makefile.
Other changes:
Removing dummy unit test and setting up window class as a framework
No longer ignoring any makefiles anywhere in the repo.
CONTRIBUTE now mentions creating issues for bugfixes
Adding a README in core with class descriptions
Adding line about design contributions
Adding DESIGN document
Adding bindable to core class list
Also tweaked description of renderers
Tweaking CONTRIBUTE file
Adding Bindable class and types header & test.
Adding GLFW and an associated test.
Adding Texture class framework and test
Tweaking build system
Tweaking README
Adding Drawable interface class
Adding resource links for OpenGL textures
Adding engine framework class.
Add EventHandler interface class framework
Tweaking README
Adding Renderer interface class
CMake for unit tests.
Still needs testing on other platforms!
CMake build system. Still working on it.