Log Message:
Update mathomatic to 12.5.11.

Changes:
- "matho-primes pal" wasn't working, fixed.
- Improved the "Equation not defined" error message for new users.
- Worked on matho-primes program.
- Automatically determine the variable if none is specified
  with the extrema command.
- Code cleanup.
- Helped simplification of complex exponentials.
- Parse things like "2 2" as "2*2", instead of giving a \ 
syntax error.
  The default operator is always times.