FMSLogo Code

Fix a bug where if OPENAPPEND couldn't read the file, it threw an error but still opened the file with an indeterminate encoding.
Now it throws an error and doesn't open the file.

Merge in changes from trunk to get GNU/Linux implementation of SHELL

Enable a buggy version of SHELL on GNU/Linux
However buggy, this unblocks test development on GNU/Linux where functionality lacking in FMSLogo can be provided by Perl.

Change references from localizedstrings-XX.h to localizedstrings-XX.txt.
The .h file is now generated from the .txt file and is no longer given to translators.

Fix typo: "a native Spanish speaker of Spanish" -> "a native Spanish speaker"

Fix typo: "etc" -> "etc."

Update the translation instructions for the Unicode FMSLogo (version 8.0 and up)
This is mostly stating the character encoding requirements of each file.

Add CSS to not wrap <code> tags.
This improves readability by preventing filenames with hyphens from being broken across lines.

Fix a typo in the instructions for startup-XXXX.logoscript.

Refactoring: Rename some local variables to make the code more readable.