Clean optimize

Depends on #8 (first two commits here will disappear).  This PR firmly plans the RTC IIC address into a ``static const``, where it's impossible to accidentally change.  It also moves all short 1-3 line methods into the header file and marks them for in-lining.  In addition to making the code faster, it also makes the code **smaller**.  The ``lcd_clock`` example went from 5346 bytes down to 5068 (under Arduino 1.0.5).