Issue title: Remove/Hide custom plugin timestamping
 Issue body: [sourceforge](https://sourceforge.net/p/oblivionworks/enhancements/235/)

Now that Bash uses BAPI for load ordering, and Skyrim doesn't use timestamps for load ordering, the ability to set custom timestamps through Bash is useless (correct me if I'm wrong), as changing the load order through drag 'n' drop or the arrow keys would cause timestamps to be overwritten by BAPI on Oblivion, and timestamps are ignored in Skyrim.
Removal of the custom timestamping features involves the removal of the File->Sort (which should never have existed...) and File->Redate plugin context menu commands, and the Timestamp field in the Modified panel. The Modified column in the main list in the Mods tab could also be removed, but I'd argue that it's still got some informational use for Oblivion. Perhaps it could be hidden by default for Skyrim.

 Comments: 
 Comment 0: Arthmoor said:

> Uber-late comment. I think this is still of value for Oblivion (and the Fallouts if Flash is ever re-integrated) since it can be a great deal faster to simply redate a file than to drag it across half the load order given the UI lag we still have.
> For Skyrim, editing it isn't useful for the game, but for the CK it is.
> As for the actual File->Sort menu, I think THAT should go though. As you say, it should never have been there to begin with.

 Comment 1: Can't tell if that comment was mine or directed at me - but yes. It's definitely handy to have for redating files to load into the CK since that still uses the timestamps.

 Comment 2: Yeah, was meant to quote you.  I was tired at the time and carried this one over for some reason, should be `rejected` since there's definitely still use for it even in Skyrim.

 Comment 3: FWIW, I now retract the enhancement request.

...Looking at the emoji available here, I see :trollface:...

 Comment 4: Using redating to move files around is pointless since d67f621278ffddaafcb4d55b735bb5a075bd9c92, but as mentioned above, redating still has other use cases.
 Comment 5: As for 'Sort', 92691409567ce020c6958325ee8c4bd8c9e820cc renamed it to 'Order By Name', so I don't think there's any more issue with it ('Sort' was definitely terrible as a name for it though, agreed).
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