Add ini option for commenting out default values

This request adds an ini option IniCommentDefaults which comments out options with default values when they are written.  It must be used in combination with IniIncludeDefaults.

Most applications which provide packages include a default configuration file which has all options with default values commented out. Just by looking at files in my /etc folder I can tell that this is a valid feature.

I find "writeGroupIni" now a little cluttered. Since <code>oname + " = "</code> is used quite a lot I would like to put it in a <code>prefix</code> variable which can be extended with a <code>"; "</code> for the IniCommentDefaults option. What do you think?

I also found some bugs which I want to address with other requests.