Extended background color mode

[xlar54]

vic.zip

This mode lets you have different background colors for characters 0-63. There were a number of changes needed to support it, including a new method that needs to also be added to the header file:

inline void draw_ext_backcolor_char(int x, int y, uint8_t data, uint8_t color, uint8_t c);

You may want to run a diff, but i think otherwise we are pretty much still in sync.