Log Message:
Update mathomatic to 12.5.10.

Changes since 12.5.8:
- Bug fix for nintegrate command.  Result was correct but not fully reduced.
- Added "twin" option to "primes/matho-primes", removed \ 
"primes/matho-twin".
- Automatically determine the variable if none is specified
  with the derivative and taylor commands.
- Increased the maximum variable length to 1000 characters.