Added lib files
Merge branch 'develop/graphics_driver' of github.com:tinyx/xv6_graphics into develop/graphics_driver

Conflicts:
	Makefile
Prepare to revert
Fix the layer buffer problem
Draw line function is now working correctly
Print text working correctly
first try of mouse driver
Finish the drawing polygon funtion
Merge branch 'master' into develop/graphics_driver

Conflicts:
	Makefile
new mouse driver but still have problem when packets are out of order
mouse reset after packet out of order
Mouse Arrow added
All changes
Merge branch 'test/mouse_driver' of github.com:tinyx/xv6_graphics into test/mouse_driver
Merge branch 'test/mouse_driver' into develop/mouse_interact

Conflicts:
	Makefile
Mouse now could interact with the graphics
fix bug: y axle movement is inverted.
record previous mouse position
Merge branch 'test/mouse_driver' of https://github.com/tinyx/xv6_graphics into test/mouse_driver
Merge branch 'test/mouse_driver' of github.com:tinyx/xv6_graphics into develop/mouse_interact