This fix a GL_INVALID_VALUE error on startup due to 0.0f max line width.
Also moves the max anisotropy filter to the sampler creation.
This reduces code fragmentation.
This is in order to disolve GPU_draw.h into more meaningful code blocks.
All the Image related function are in `image_gpu.c`.
All the MovieClip related function are in `movieclip.c`.
The IMB module now has a connection with GPU. This is not strickly
necessary and the code could be move to `image_gpu.c` if needed.
The Image garbage collection is also ported to `image_gpu.c`.