free cache only as needed rather than a complete reset
improve coordinate calculation accuracy and add floating point precision (as needed for smooth overzooming)
a few minor optimizations
optimize box text for point pix
draw quiting for opengl
remove debugging code
copy the plugin icon as a convenience for future plugins

this allows future plugins to share the toolbar and plugin icon object without making multiple icons
it must be copied to avoid being freed twice
remove unused code
detect opengles, and add options for profiling
refresh toolbar only if needed