Room creation commands now default the new room's typeclass to that of the caller's location

[chiizujin]

Brief overview of PR changes/additions

The comments in ObjManipCommand.get_object_typeclass state:

For instance, when using dig, the system can use this to autodetect which kind of Room typeclass to use based on where the builder is currently located.

However, this is not the case as rooms are always created as typeclasses.rooms.Room if no typeclass is specified.

This PR adds that behaviour.

Motivation for adding to Evennia

"New" feature.

Other info

I'm not sure whether or not this should be included as it changes the default behaviour of some commands, though the comment suggests that this might have originally been intended. Or maybe it was removed at some point and the comment wasn't updated.

Examples

Before

>ex
--------------------------------------------------------------------------------
Name/key: cave (#13)
Typeclass: TestRoom (typeclasses.rooms.TestRoom)
(...)
>dig/teleport cave2
(...)
>ex
--------------------------------------------------------------------------------
Name/key: cave2 (#14)
Typeclass: Room (typeclasses.rooms.Room)
(...)

After

>ex
--------------------------------------------------------------------------------
Name/key: cave (#12)
Typeclass: TestRoom (typeclasses.rooms.TestRoom)
(...)
>dig/teleport cave3
(...)
>ex
--------------------------------------------------------------------------------
Name/key: cave3 (#15)
Typeclass: TestRoom (typeclasses.rooms.TestRoom)
(...)

>ex
--------------------------------------------------------------------------------
Name/key: cave2 (#14)
Typeclass: Room (typeclasses.rooms.Room)
(...)
>dig/tele cave4
(...)
>ex
--------------------------------------------------------------------------------
Name/key: cave4 (#16)
Typeclass: Room (typeclasses.rooms.Room)
(...)

dig/teleport cave5:typeclasses.rooms.TestRoom
(...)
>ex
--------------------------------------------------------------------------------
Name/key: cave5 (#17)
Typeclass: TestRoom (typeclasses.rooms.TestRoom)
(...)

>tunnel s=cave6
(...)
>s
(...)
>ex
--------------------------------------------------------------------------------
Name/key: cave6 (#18)
Typeclass: TestRoom (typeclasses.rooms.TestRoom)
(...)

[Griatch]

This a nice and reasonable take from the given info, but afaik the dig command never worked this way. The text in the ObjManipCommand is unfortunately phrased, it's just meant to be a possible way the hook could be used to tweak a command's function.

So thanks for your work on this, but I won't merge this one, I think it would break backwards compatibility too much. I will rephrase the docstring to have a clearer intent.