[WIP] Introduced Channels modifiers

UI Editor: done, values calculation: done, templates save/load: done.
  Missing: attach to a channel and save to project, universe check for modifiers.

Code cleanup to retrieve user/system directories from various places of the code
Updated translations
Plugins/Peperoni: added mutex locker to sync simultaneous input and output
[WIP] Channels modifiers: written Universe code to assign and use a Channel Modifier
[WIP] Channel Modifiers saved/loaded on project XML.

Completed ChannelSelection visual aspect too.

TODO: actually apply the modifier to Universe
TODO: Find a nice way to unassign a modifier