rewrite draw_text to use new viewport buffer
set_viewport now accepts rliimage to allowe interfacing with rb. functions
fix long standing 2-bit bug with text drawing in lua
fix 2-bit img
saving bug (i'm guessing just a one off, just enabled clipping)
fix font_getstringsize bug
fix shape of numbers draw_num.lua also add auto centering
add page scrolling to printtable
add a new demo script 'stars'
Change-Id: I866905cee82ee89ebc0eb020a56a7ecdb101bf5e
