FMSLogo Code

Fix a leak in BENCHMARK.PLIST.
Instead of erasing the property list, it erased a variable with the name of the property list(which didn't exist).

Fix a build break when using wxWidgets 3.0.4.
Apparently wxSTC_KEYMOD_CTRL hasn't been back-ported to the 3.0.X branch.

Update FMSLogo to from wxWidgets 3.1.0 to wxWidgets 3.1.3.

The main reason for this is to get a bug fix for Unicode command line processing that will enable me to remove a hack in fmslogo.cpp. However, it's also good to stay up-to-date on libraries to minimize the number of problems caused by each upgrade.

This library update cooresponds with a major version number increase in FMSLogo from 7.7.0 to 8.0.0. It's good to include a potentially disruptive change to a library in major version increase, since it's somewhat expected that things will be incompatible and possibly be broken.

Remove gbm_guess_filetype() and extension().
These used deprecated forms of wcstok() which are not available in modern C++. More importantly, they caused build errors when compiling on GNU/Linux.
Fortunately, neither of these functions were used by FMSLogo, so it was easier to remove them than to fix them.

Change wxSTC_SCMOD_CTRL to wxSTC_KEYMOD_CTRL.
wxSTC_SCMOD_CTRL is deprecated in wxWidgets 3.1.3.

Call SetCursor directly form OnSetCursor() instead of calling into lsetcursorarrow()
Calling into the Logo engine, which then called back into CMainFrame was not only convoluted, but also causes a shutdown crash on wxWidgets 3.1.3.

Fix minor typos (missing period, wrong tense)

Remove the "unicode" branch, now that it's be integrated into trunk.

Remove gbm_find_word and gbm_find_word_prefix
These functions were not used by FMSLogo and needlessly contributed to size and maintainence cost.

Fix the GIF* API to accept Unicode filenames.

The gbm subsystem which implements GIF used the POSIX I/O functions (open(), read(), write(), etc.), so this involved porting it to use the C stdio routines (fopen(), fread(), fwrite(), etc.) and using wxFopen, which supports wide characters. It also involved changing an int file descriptor to FILE* and using wchar_t instead of char wherever filename are used. As a result, the files underwent sweeping changes, even if only a few are significant.