fix old framebuffer API usage in input_android

the Android input module triggers refreshes under certain circumstances.
This was not considered when refactoring the framebuffer API.
remove superfluous require()
add refreshUI() implementation

another refresh method
fix blitbuffer test

got broken when we changed default from 4bpp to 8bpp
Merge pull request #275 from hwhw/master

Fixes for refresh refactoring