The console command ShowVars does not list global mwscripts

in original morrowind, the console command ShowVars will (when called without a target) list all global variables, followed by a list of currently running global scripts and their variables. openmw (0.49) does only the former.

reasons to do the latter:

1. when called with a target, the command lists variables in attached local scripts. so the global behavior should take global scripts into account.
2. it is useful for debugging quests controlled by global scripts. in fact, far more important than listing global variables, since they are too many to read, and we have the command Show for global variables (which does not work on script variables).
3. to be consistent with original morrowind.