Added support for font files in SPI FLASH.
Removed program memory font files.

Media files in SPI FLASH now have a 16-bit type field.  They can
be either a MEDIA_BITMAP or a MEDIA_FONT.

the oledSetFont(id) function now treats the id as a media file index.

Timing: With profont_10, speed per character has dropped from 1msec to
1.3msec.  This should be able to be improved.