compton-conf: Some issues

[richardgv]

Just a few random issues I noticed. Of course, you are probably already aware of most of them. It's the first day and I shouldn't expect too much. :-D

1. It doesn't display correct default values when a configuration file is present but a specific option is missing. For example, menu opacity will be displayed as 0.0 if I comment out menu-opacity = 0.8; in my configuration file.
2. Many people keep their configuration file in~/.compton.conf, and you may wish to take care of it. (A lot easier with Qt than in C!) The configuration file could be in /etc/xdg/compton.conf, as well. You could query what configuration file compton is reading right now with dbus-send --print-reply --dest=com.github.chjj.compton._0 / com.github.chjj.compton.opts_get string:config_file when it's running.
3. When converting displayName, isLetterOrNumber() should be used instead of isNumber(), since compton replaces all non-alphanumeric characters with underscores when representing display name.
4. All comments are lost once compton-conf writes to the configuration file. Heh, that's a problem of libconfig, and I guess you can't do much about it.

[agaida]

Still there - same as in the "resonable defaults" bug