Use negative count to map pixels in reverse order along
a strip.

Offering details on how to use a new config file

The "zigzag" argument is handy to create daisy-chained grids, but what
if we want to start from the other side? I don't think rotation gets us
there, but this does.

Correct reserved bits line now that bits 2 & 3 are specified.

Details of how fcserver and the controller operate

This was a doc typo, Fadecandy uses the standard OPC command number of 0x00.

Fixes issue 21.