Added LED muxing and ADC converters

Added array multiplexing for leds, doing one shiftreg for r/g/b and one
for leds 1-8. need to check what current we can/need to give at the
resulting low duty cycles.
Added user-selectable ADC voltage divider for use with -5-5v input
ranges, also added simple low-cut. Need to verify the values for the R
in the divider and the RF cut lp.