Code review comment for lp:~gcrosswhite/leo-editor/fix-haskell-support

At the moment, support for Fortran 90 in Leo is a touch problematic. Although Leo is smart enough to recognize "@language fortran90" and to use "!" for comments instead of "C", there is no corresponding color mode file so that syntax coloring is disabled.

To correct this problem, I have created "fortran90.xml" and "fortran90.py" in leo/modes (the latter being generated from the former using the jEdit2py script), which are essentially just tweaks of the existing "fortran" mode with modified comment characters.

While I was at it, I also modified leoApp.py to make Fortran 90 specifically be associated with .f90 files, and Fortran associated by default to .f files.