MSP430 Improvements

[brackendawson]

• Significantly reduce memory use, makes all patterns work on MSP430. fixes #10
• Fix mode button on MSP430, interrupt was not enabled.
• Reduce clock speed on MSP430 to calibrated 16MHz. fixes #4
• Correct internal timer rates on MSP430.
• Enable watchdog timer on MSP430.

[brackendawson]

I checked it twice and tested it on all three architectures.