Fixed|Savegame Tool: Off-by-one error in naming of converted Hexen map state files

Note that any previously converted savegames will need to be removed
so that the originals will be reconverted.

Also fixed a Chex Quest specific map URI translation error.
Merge branch 'master' of github.com:skyjake/Doomsday-Engine
Savegame Tool|NativeTranslator: Extract more metadata from legacy Hexen savegames

The present player list and time in the current map is now extracted
from old Hexen savegames and included in the metadata (the Info file)
similarly to the other games. While Doomsday does not currently use
these with Hexen it is useful info that belongs in the metadata (and
also avoids having to retrieve it from the map state data file).