32-bit support, redundant code removal

This change makes the basic MMA8452 example work properly on 32-bit boards.  Tested on a Teensy 3 and confirmed to still work on an ATmega328-based Arduino clone.

Also removed a double negation of gCount:

    gCount = ~gCount + 1;  // bitwise negation of gCount
    gCount *= -1;          // arithmetic negation of gCount

So why does the code work anyway?  Because in C a right-shift on a signed integer is an arithmetic shift, meaning it handles negative numbers the way you would want for gCount in this application; (-4 >> 1) == -2.