Promote 3/3/3 RGB to Adafruit_GFX 5/6/5

Promote 4/4/4 RGB to Adafruit_GFX 5/6/5

Demote 8/8/8 to Adafruit_GFX 5/6/5 If no gamma flag passed, assume linear color

Constructor for 32x32 or 32x64 panel:

Return address of back buffer -- can then load/store data directly

Dump display contents to the Serial Monitor, adding some formatting to simplify copy-and-paste of data as a PROGMEM-embedded image for another sketch.

For smooth animation -- drawing always takes place in the "back" buffer; this method pushes it to the "front" for display. Passing "true", the update