Sets a new value for a .htaccess Maker configuration setting.
For keys which store a single value the syntax is
For keys which store a list of values, such as a list of directories, a list of file extensions etc you have the following alternative syntaxes:
--option=something --empty to remove all
--option=something --add=whatever to add
whatever to the list of values
--option=something --remove=whatever to
whatever from the list of values