Log Message:
Update mathomatic to 12.1d.

Changes since 11.7:
- Increased precision and optimization of code command.
- Prepared code for future improvement to integrate command.
- Integrate (a*constant^x) for x has been added.
- Allow differentiation and integration of -constant^x.
- Disabled power factoring of k^x*k^y, where k is a constant.
  This fixes a small bug.
- Reduced stack usage by almost 2/3.
- Reduced stack usage another large amount to the smallest it can be.
- Laplace (a*constant^x) and (a/constant^x) for x has been added.
- Allow integration of (a/constant^x) for x.
- Moved all numeric GCD routines to "gcd.c".
- Improved limit command for "limit x inf".
- Halved the default equation size and doubled the number of equation
  spaces to 40.
- Fixed bug that caused infinite loop for "2^(.5*n)" and incorrect answer
  for "-1^(2*n)".
- Allow edit command to work with no equations defined.
- Allow typing "abort" or "quit" during pause command.
- They both abort the current operation.
- Removed usage displayed every time a command fails.
- Simplify command once again prefers 1/(constant^n) instead of (1/constant)^n.
- Added "set finance" option.
- Some improvement to simplification of constants.
- Improved "factor number" command.  Made self-testing and allow
  multiple integers.
- Strip trailing newlines from string returned by getstring().
- Re-enabled power factoring of k^x*k^y, where k is a constant.
- The bug it had caused just disappeared.
- This is because a lot of changes have been made.
- Some speed up in polynomial factoring made by ignoring anything that
  is not a polynomial in any variable.
- Improved denominator rationalizer.
- Disabled power factoring of -1^x*-1^y.  This time it is done right.
- Added new function debug_string().  It simplifies the debugging code.
- Simplified pf_sub() (the polynomial factoring subroutine).
- Fixed up Prime Number Tools man pages.
- Improved matho-twin.
- Added simplification of roots like 12^.5 to 2*(3^.5) in simplify command.
- Code cleanup.
- Improved the results of solving by not always factoring constants.
- Added semicolon (";") to end of each line when using "list \ 
export".
- Some improvement made to the simplify command.
- More tests added to test suite.
- Fixed bug in patch_root_div().
- Fixed infinity/nan bug in uf_repeat().