[CM] Snd 12.10

[Bill Schottstaedt]

Snd 12.10.

This version is mostly bugfixes and documentation improvements.
In s7 "@" is now an exponent marker.

checked: gtk 3.3.18|20|3.4.0, gmp 5.0.4, mpfr 3.1.0, cairo 1.12.0

Thanks!: Jeffrey Zimmer, Sean Reed, Michael Edwards, Peter Bex.