Write characters with color descriptors to virtual display
void SLsmg_write_color_chars (unsigned short *s, unsigned int len)
The SLsmg_write_color_chars function may be used to write
len characters, each with a different color descriptor to the
virtual display. Each character and its associated color are
encoded as an unsigned short such that the lower eight bits
form the character and the next eight bits form the color.
SLsmg_char_at, SLsmg_write_raw