Enabled built-in pull ups

Enabled built-in pull down resistor to better stabilize the SW input.
Testing if I still need an external pull-down but for now added one in
the schematic.
Fixed issues

Fixed several issues.  In the schematic added pull-down resistor and
also some caps to improve performance and noise issues.  Re-wrote the
temperature reading routine and color picking.  Enabled the internal
voltage reference and set to 2.56 VDC reference voltage.  This means the
values won't change as the battery voltage drops over time.  Cleaned up
various parts of the code.  Tested to work so far on the rev1 boards.