Change confirmation message for deleting multiple blocks

Change-Id: Ibe50fc8076be589ea377af1a1c45e6a386b1f6c8
Arrange for keyboard to not cover element that has UI focus

Change-Id: I92fd8e5d281ea04f52d6d4677c896b8b57d1647a
Add Volume property to VideoPlayer (setter only, for now).

Change-Id: Id151f9f2db96437a69015d078bb803348ab26a7c
Merge branch 'master' of https://github.com/mit-cml/appinventor-sources