Update to 4.40

ChangeLog:

• Added 6 combining accents as separate characters.
• Added 14 letters with dot above / dot below.
• Added partial subscript and superscript: all digits and 11 letters.
• Added 30+ math characters, notably large braces, brackets and parens.
• Added unicode range 2800-28FF in two variants (br1 and br2).
• A few small character fixes.
• Altered configure to be a bit more POSIX compliant.
• Replaced some obscure (un)install Makefile targets with variables.

Committed from: EuroBSDCon 2015 DevSummit