avoid the need for replacing backslashes with slashes on windows for some settings

This is my fix, kindly tested by @chadaustin, for the problem where passing a setting using Windows file paths and the first character of a directory name or file name was ``n`` would cause things to break.

The issue where we had this was for a setting for the ``SHELL_FILE`` and it was in ``C:\imvu\northstar\... and this was getting converted to newlines, causing things to choke and die.

This was discussed on IRC with @kripken and @juj as well.