Fixed documentation in source for Android.
Fixed writing new errors to standard output instead of error output on Android.
Fixed typo in message of alert dialog for not loaded libraries on Android.
Fixed upper case button in alert dialog for not loaded libraries on Android.

This is more consistent with the buttons of other dialogs on Android.
Fixed missing @Override annotation warning in source for Android.
Fixed alert dialog for not loaded libraries on Android being cancelable.

If the alert dialog could be canceled the Activity would not be finished here.
Also setting the property to "true" would be redundant because that is default.
Added an option to define libraries to be loaded on Android in a derived class.

This way it is no more needed to modify SDLActivity.java to add own libraries.