Fix Issue #470 - Single-pixel stripping (#478)
Fix Issue #470 - Single-pixel stripping (#478)

Points now track `firstColored` in addition to `lastWhite` and `lastColored`.  If a point has `firstColored` *and* `lastColored`, it's a single colored point and its offset shouldn't be adjusted, otherwise it will have the same coordinates of the preceding point which is invalid.
LaserWeb/LaserWeb4,LaserWeb/LaserWeb4,LaserWeb/LaserWeb4