2.0 Update for Advanced CRT Shader

I've refactored the code to improve performance and greatly enhance the realism of the CRT effect (see images). 

• Added the ability to capture user-specified draw events and include them on the CRT screen, fixing the GUI sizing issue some users were reporting.
• Ensured that all blending operations are now gamma-correct, improving color accuracy and playing more nicely with HDR.
• Took phosphor masks back to the drawing board and came up with a much more flexible solution requiring fewer textures.
• Added beam dynamics, adjusting the size and shape of scanlines depending on the energy of the beam.
• Reworked the reflective screen border, allowing users to customize its size and material properties.