Add application category for OS X

The Applications folder in OS X is large and installers tend to expect apps to stay where they were placed (i.e. the root of /Applications). Since Lion, there's been application category metadata for View --> Arrange by Application Category but if the metadata's not in info.plist, the app gets sorted into "Other" at the bottom. 

https://developer.apple.com/library/Mac/releasenotes/General/SubmittingToMacAppStore/#//apple_ref/doc/uid/TP40010572-CH16-SW8 (this applies to all Mac apps, not just those installed through App Store).
If SelectedIf is in a list of Actions, it is uesd to check selected
If SensitiveIf is in a list of Actions, it is uesd to check sensitive
fix selected status in musicroom
Create common.rpy

testing how to add Arabic translation to the templates in Renpy
Create screens.rpy
Create options.rpy
Create screens.rpy
Create script.rpy
Create about.rpy
Create add_file.rpy
Create android.rpy
Create choose_theme
Create common.rpy
Create distribute.rpy
Create distribute_gui.rpy
Create editor.rpy
Create front_page.rpy
Create interface.rpy
Rename choose_theme to choose_theme.rpy