Add all submodules to IDEA.

Exclude the modules directory, this makes them show up as top-level entries.

Change-Id: Ied2ac11d2b5f8dee25808ffaec95052051e875f9
Reviewed-on: http://gerrit.dmdirc.com/3700
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>