performance upgrade

changed internals to use a single Uint8Array instead of nested arrays

added two renderer
- basic renderer replaces fillRect() code with simple loop & putImageData()
- WebGL renderer using simple shader to upscale

reworked sprite/blitting to new model
- but without alpha: needs some architectural decisions

added hacky speedtest.html with stuff to demo & test performance
added some ImageData & reset helpers
moved character code to bottom of class
applied quotemark lint fixes