Persist match settings should only save some settings

[elexis]

Currently the persist-matchsettings function (see gamesetup.js) store all mapsettings and load it the nexttime.

But some tags shouldn't be saved.

• For example this author tag removed in r17980 was present in every replay due to this bug once the map was started once.

• Another example is DisabledTemplates. Belgian Uplands is the only map that disables the ptolemian lighthouse. But the persistmatchsettings will save this value and when selecting a map that doesn't set it, it actually disables them due to the remains in the persistmatchsettings-file.

Only known settings (which can be changed by the host) should be restored - every other setting ignored (notice on skirmish and scenario maps, less settings can be changed).

[elexis]

In order to remove unintended tags, loadPersistMatchSettings() in gamesetup.js needs to delete all properties of the attrs object which can't be changed by the user.