Store project names separately

Nice idea, I have used `geany -c projectdir` in the past for projects that needed configuration beyond that available in projects (I may have mentioned that projects should store all configuration ... repeatedly :).

The downside is that you can't easily swap from project to project when using `-c`, you have to start a new Geany/cleany by either knowing the path to the config or cd-ing to the project dir.

If your script saved project names vs project dir in a known place then `cleany projectname` could look up (or create if not existing) the project directory and cd to it before running Geany with suitable arguments.

I assume using both -c and a project is for the benefit of the project plugins?