Sebastian Reuße authored Jun 12, 2015 and Thomas Miedema committed Jun 12, 2015

The alternatives table gave the wrong glyphs for LEFTWARDS resp.
RIGHTWARDS ARROW-TAIL notation. The listed codepoint was correct,
but the entities corresponded to characters different from those
codepoints.

This also adds the glyphs for LEFTWARDS resp. RIGHTWARDS
DOUBLE ARROW-TAIL, which were formerly missing, and the PROPORTION
glyph, which was formerly given as ASCII.