Cleaned up CONFIG_CENTRUM_xxx switches:

Cleaned up CONFIG_CENTRUM_xxx switches:

  o  Everything related to the catalog is controlled by
     CONFIG_CENTRUM_CATALOG.
  o  Paid weights are implied by the catalog and the PL customization,
     which doesn't use them, just defines empty {get,set}_paid_weight().
  o  Nothing depends on CONFIG_CENTRUM_{CZ,SK,PL} now, but I am keeping
     them, because it's likely that it will be needed for some exceptions
     or experiments again soon.

All customizations compile except for centrum/* with shared libraries,
but the dependencies for that are already fixed in the dev-analyser branch.