Finalized DialogTree: should now be ready to interact with pickup

Finishing touches on DialogTree include:
-DialogTree now properly turns on and off the pickup script.
-DialogTree, for some menus, will now display the response text instead of
the original prompt text as subtitles when the action sequence is enabled.

However, it's important to note that there is now a global variable in
Settings.debug called start_allow_actions. If this is turned on (which it
is right now) it means that the pickup script will be turned on
immediately when the game starts. This is for debugging. In the real game
we want it off at first and only turned on in certain parts of the menu
sequence. To have it turn off at start, set this variable to false. Make
sure to do this for the real demo. In fact I may enforce this with
Application.isEditor in a future commit.