ProperTree.command should perform Tk version detection

[Artoria2e5]

buildapp-select.command currently includes a bit of Tk version detection logic. This should really be also incorporated into the Python selection logic of ProperTree.command.

[Artoria2e5]

Heck. Assuming that the Tk+Python detection logic in that thing can be made pretty good, why do we even include a select step before building an app? Just make an app that open -a Terminal.app /path/to/self/Resources/ProperTree.command and that's it.