This avoids having to keep around global variables (such as epresent--org-file)
and hoping that they won't get corrupted between presentation start and
presentation stop, which might interfere significantly with the intended
functionality of the mode.
Note that I have not yet tested this, only sketched it out in a way that I think should work. I'd like further input from more experienced Emacs users before moving on with it.
This avoids having to keep around global variables (such as epresent--org-file) and hoping that they won't get corrupted between presentation start and presentation stop, which might interfere significantly with the intended functionality of the mode.