Added function to rotate display 180 degrees.
Changed to use get_ for getters, added contrast control.
Updated sample to new fn names.
migrated worker thread logic for led sequences from timeclock into gaugette.
Migrated worker logic from timeclock into gaugette lib.
Fixed off-by-one bug in display_cols, added new display option using external buffer class.
updated rotary encoder tests.
Separated bitmap buffer handling into subclass of ssd1306, and added scrollable list helper class.
Merge branch 'dev'