Add stub header files for a rendering framework

- Implement shader
More shader class

- Add documentation
- Rename GetErrorLog to GetCompileLog
Partial implementation of program

- Still need to retrieve vertex attributes and uniforms
- And provide a way to query them
- Removed old GLProgram class
More program implementation - Uniforms

Retrieve list of uniforms on program creation and store in an array
Program - Vertex Attributes
Program - Uniform and Vertex Attribute Getters