add the extra functions for drawing gui elements
RoundedRectangle:
All draw rect functions now pass through roundedRectangle which uses a shader and can draw borders, and rounds the corners
Draw thick line:
draws a line thicker than 1 pixel, uses a geometry shader to do this
Draw Circle:
Draws a circle with a border parameter.
Adds the ground work for geometry shaders
Expands shaderData and gfxShader to allow for more shader types
note: when building a GFXShader in source you have to call setShaderStageFile with the shaderStage and the filepath for that stage.
Once we add compute shaders this will become more apparent as compute shaders are a stage of their own and do not require vertex and pixel files whereas other shaders sometimes do.
