Re-structured PP Strip, 16-bit component bugs, red/green/blue global brightness, type-mismatch warnings

• Re-structured PPStrip to convert RBG values of various types to a table of bytes as these values are presented, rather than when [PPStrip serialize] is called.  After this, the code that presented the values (in uint8s) ran twice as fast, and [serialize] probably ran 100x as fast since all it does now is copy a block of bytes.

• Fixed recent code written to handle 16-bit RGB components (not tested yet since we don't have the 16-bit hardware yet!)

• Expanded the global brightness properties in various classes to handle separated brightness adjustments for red, green, and blue.

• Fixed a few type-mismatch warnings, particularly ones where an unsigned int was compared to a signed int.

Signed-off-by: schardt <github@schardt.org>