Enhancements discussed on intfiction.org

[DavidGriffith]

This patch represents the changes that zzo38 made to glkterm as presented in https://intfiction.org/t/enhanced-glkterm/14049. I processed that code into something that could be merged into the regular codebase.

Here is a list of some of the new features:

• Can use a .glktermrc file to store user preferences
• Can display “More” when paging
• Support paging when glk_exit() is called
• Colours are supported
• Can set read-only mode; most files opened by Glk fileref functions are read-only
• You can also prohibit all file access entirely
• Filename mapping
• User-definable styles
• Can disable mangling of filenames entered by glk_fileref_create_by_prompt()
• Can set clock skew for the Glk date/time functions
• VT100 line graphics for window borders
• New command-line option – which makes it to treat further arguments as plain arguments (so filenames can have - at first)