Add memory buffer support to adafruit graphics

[davetcc]

Add memory buffer support for Adafruit GFX based displays as an option. For TFT displays adafruit can look a little flickery, this is because we are first clearing the display then putting menu items onto there.

This is to do the same thing as we do for TFT_eSPI, where we draw into a buffer first, then regardless of display performance, flickering is reduced.

[davetcc]

This provides a huge performance increase for menus on adafruit libraries, at least one if not two orders of magnitude in some cases.