BIOS should be code page agnostic

[thejpster]

Functions that return strings should be ASCII only.

The docs for setting a font should note that no particular code page is supported and that it is a function of the font. The only limitation is that the code points are 8 bit, for memory reasons. Although I guess a BIOS could offer a UCS-2 or even UTF-32 text buffer of they wanted to? How does XTerm et. al. store a grid of Unicode characters, handling accents and other modifiers?

We should also add support for enumerating and selecting hardware fonts, as well as passing in a soft font.

[thejpster]

Alternatively, accept that fonts only have 256 glyphs, and use UTF-8 for all strings - mapping Unicode code point to glyph as the text is written to the screen RAM.