replace glyph list loader

Karl Berry made us aware that our generated version of ``font-age.lua``
differs from the Context/Luatex-Fonts one and should be renamed. It’s
trivial to do so but invasive still. This workaround may have to be
adapted if Hans chooses to rewrite the Glyph List loader.
fix redundancy in Makefile
adjust font sizing with nonstandard em sizes
Merge pull request #50 from phi-gamma/master

``font-age.lua`` -> ``luaotfload-glyphlist.lua``
also address issue #51