Mathomatic 15.4.1

1/13/11 - Upgraded the plot command towards always giving gnuplot a proper plot command,
          no matter what the user input is. The plot command now automatically renames the
          variable in a single variable expression to the x variable, so plotting
          will always succeed.

          All makefiles were modified to allow the following:
          Setting CFLAGS when building now allows manually specifying the program
          optimization you want. It is also the way to add compile-time options
          and macro definitions. Suggested by many package maintainers, thank you!
          If CFLAGS is defined as the empty string, all optimizations are turned off.
          New optimizations can be added to the CFLAGS string during builds,
          overriding any default optimization in the makefile.

1/14/11 - Removed Python script "misc/mp"; Couldn't get mpmath to work properly for
          all input.

          Improved results of the fraction command.

1/15/11 - Now saving readline history in $HOME/mathomatic_history when compiled for CygWin.
          Now additionally searching for "mathomatic.rc" in $HOME when compiled for CygWin.

1/16/11 - Ported matho-pascal and matho-primes to double floats if USE_DOUBLES is defined,
          for systems that don't support long double floats.

1/21/11 - Linking with library "curses", instead of "ncurses" now, as required by Solaris.

          Removed an indeterminate test called linear.in that was flunking "make test",
          due to slightly different, though correct, results on various systems.