Refactored GL initialization code into its own file.
Added OpenGL program and vertex shader initialization code.
Added a simple fragment shader, and fixed some small bugs.
Removed some deprecated rendering code.
Refactored certain code sections into their own functions.
Added the structure to initialize VBO's for rendering.
Added code to inialize and render the frame using VBO's.
Fixed various rendering bugs.

This commit fixes various issues in our OpenGL rendering code, so now
the spectrogram legend frame is rendered properly.
Added code to allocate a VBO for the spectrogram itself.