investigate main led timer adjustment

[dhiltonp]

Investigate timer modes as they relate to:

• reducing the intermittent flickering when changing between high and low modes
• power consumption changes
• light intensity changes at a given level

[dhiltonp]

I've tried waiting for TCNT1 to be low, but still had flicker. It may be related to this problem: http://jeelabs.org/2010/01/06/pin-io-performance/

This is partially addressed by this: http://code.google.com/p/arduino/issues/detail?id=140