- "Externally added files can be added to Git" notifications in Android Studio won't be displayed regarding build output files.
- "git status" won't list irrelevant build files.

Common/build/outputs/mapping/*/mapping.txt will still be generated. (That file will contain exactly what Common/printmappingout.txt would have contained.)

(The original reason to modify Common/proguard-rules.my was to stop an output file (printmappingout.txt) being written in a directory where source files are stored.)

Android Studio would show a notification window regarding an invalid path when the project was opened for the first time if the SDK couldn't be found at the location specified in local.properties. (local.properties specified the Android SDK directory as '/home/jka/Android/Sdk'.)

Now, with no local.properties file in the git repo, there's no notification about an invalid SDK directory when opening the project for the first time. A new local.properties file specifying the correct SDK directory is created when the project is opened.

If there's a need to regenerate the local.properties file after pulling this commit one can do that by clicking on "File / Sync Project with Gradle Files" in Android Studio. (The Android SDK directory can also be specified using the ANDROID_HOME environment variable.)

The first line of the local.properties file was:
    ## This file must *NOT* be checked into Version Control Systems,

local.properties was added to .gitignore in f53ea03.