add first pieces of support for webGL maps
move GL map rendering stuff into an object
move map-related variables into gMap object, move GL tile drawing into its own function, rename old GL drawing function to a test name, put a 'real' drawing function in its place by cloning the 2D one and commenting out currently unsupported functionality
more progress on actually painting a map with GL, something is still flaky though
remove 2D canvas, move draw() and resizeAndDraw() into gMap, only use stored position if it has all three components set
separate assembling and drawing functions and make the latter happen on requestAnimationFrame, fix bugs to make everything run nicely
old pixels optimizations are not needed any more, determine if we even go to tile cache by querying texture list
remove separate tile indexes array and use a direct tilekey->texture array instead
implement cleaning of textures
adjust TODO for GL implementation