Fix for obj_1.depth = 10; crashing when obj_1 isn't in the room.
Resolves #772 to allow access to inherited vars

Bubbles up the parent chain to see if an inherited variable should be
included when building the dot access list.
Merge pull request #796 from Heathtech/master

Resolves #772 to allow access to inherited vars
Merge pull request #793 from sorlok/depth_crash

Fix for obj_1.depth = 10; crashing when obj_1 isn't in the room.