Save to BMF.

[JoeStrout]

Right now, if you press S to save your work, fontEdit simple writes out the current glyph in PNG format (though in a file with the font name, ending in .bmf). This is obviously wrong.

bmfFonts.Font already has a save method (used by the pack.ms utility script). So it should be a simple matter to make the Save function actually save the whole font, in proper BMF format.