Intellivision STIC support

[robin-raymond]

Some documentation:
https://www2.intvprime.com/intellivision-faq/intellivision-faq-section-2-0-hardware/
https://en.wikipedia.org/wiki/Standard_Television_Interface_Chip
https://wiki.intellivision.us/index.php/Main_Page#Hardware
https://wiki.intellivision.us/index.php?title=BACKTAB
https://en.wikipedia.org/wiki/General_Instrument_CP1600
https://wiki.intellivision.us/index.php?title=STIC
https://wiki.intellivision.us/index.php/Graphics_ROM
https://wiki.intellivision.us/index.php/Picture_Encoding
https://wiki.intellivision.us/index.php?title=Cartridge_Port

Related PR:
#30

Related issue:
#8

FYI - Support was added for dithering and creating a .bin for use with the Intellivision. However, without an emulator to go with it the .bin output cannot be verified. It's coded to be correct (and sanity checks were performed) but may not be accurate without full testing.

Support adds:
FGBG mode (GRAM only available [due to limitation of 64 tiles])
Color stack (using GROM, GRAM, GROM+GRAM)
And single color stack / global background color mode

[robin-raymond]

Support for the STIC is now merged. However, there's no emulator so the binary output is untested. Please feel free to provide feedback.