Address U. F. O. shortcomings.

This attempts to address a number of issues mentioned in #1653, specifically the dropping of version data, the changing of glif names, and the reversal of reference and anchor orders. It also enables layered U. F. O. output in certain limited contexts outside of the specification.

If we add characters from the feature file, the core typeface that we output may have more glyphs than the one that we read. So we don't do that now.