Explicitly set FragColor alpha to 1.
Fix noisemaker imports.
Remove silly symlink.
image-viewer uses new width/height attributes.
model-viewer uses iqm.glsl shader asset.
Framebuffer Object support!

This patch makes a number of large changes in order to facilitate clean
FBO support. Texture is broken up into a base TextureAttribute class,
which is used by the Framebuffer object to implement ColorBuffer and
DepthBuffer.