Resubmitting request for issue #1361: added command-line support for Android mode only

Hi, @benfry!
Resubmitting with android-related changes only. 

As I see, `processing-java` is copied from `processing` script during the build process. But I didn't touch `build/build.xml` for `processing-android`. I'm not sure If you want android-related code there now.


`//... from the previous pull-request:`
I added `processing.mode.android.Commander`, which can be used for Android command-line build.
And here's the corresponding shell-script: `build/linux/processing-android`. It is the same as `processing-java` but calls another class at the end.
```
Command line edition for Processing 0217 (Android Mode)

--help               Show this help text. Congratulations.

--sketch=<name>      Specify the sketch folder (required)
--output=<name>      Specify the output folder (required and
                     cannot be the same as the sketch folder.)

--force              The sketch will not build if the output
                     folder already exists, because the contents
                     will be replaced. This option erases the
                     folder first. Use with extreme caution!

--target=<target>    "debug" or "release" target.
                     "debug" by default.
--build              Preprocess and compile a sketch into .apk file.
--run=<d|e>          Preprocess, compile, and run a sketch on device
                     or emulator. Device will be used by default.

--export             Export an application.
```