Example 78: Refactor __main__ into a separate main module.

This required a few fixes. This change will allow buildozer to pick up the main file in order to build android .apks.
Example 79: add a __version__ spec.
Add generated boilerplate buildozer.spec.
Example 80: Tweak buildozer.spec for orkiv.
Example 81: Tweek location of icon and sound files so that they work on android.

This probably breaks them for the 'python orkiv/' case, but we can fix that later.
Example 82: Disable sound playing.

This is causing a hard crash on android, probably due to a bug in Kivy. Disable for now and hope it's solved in a future release.
Example 83: When comparing the mode, use display indepedent pixels.
Example 84: Supply an optional root_dir parameter so that the app can be run from __main__ and main.py