Open source release of MIT App Inventor version 185a

Update Companion Version to 2.60

Change-Id: Ifd5df82e0e60abb256edb2e5f17cf7d682c5d9d5

Update Companion Version to 2.59

Change-Id: I9e15974cbe5dfcb0432a2ba33d702110d3f74cc4

Remove Column and Row properties from Form

Change-Id: I986ce001d40ff7ea4423e7a21d29e3fad3e2eabc

Add missing READ_EXTERNAL_STORAGE permission for Player and VideoPlayer

Change-Id: Icebd59c7b7a7e112f42514a3531cb78ef1537c01

Another fix for WebRTC

Cleanup the code that deals with detecting connection failures. This
change results in a more stable experience on Firefox. It also ensures
that any closed WebRTC connection is cleaned up properly. This means
that if the Companion disconnects due to the Companion being closed, or
a network failure, a new connection can be made reliably without having
to reload App Inventor in the browser.

Change-Id: I35ccba26729d7c870201165cb3821991a6f523ee

Update Companion Version to 2.58

Change-Id: Ib4d3034c2ce901b26d03f26afb43943f3bef44d2

Restore HeightPercent for Slider

Change-Id: Iefc8b15e7064d8f460865a77aca2bcdbcf244f65

Update Companion to version 2.57a

Change-Id: I85ac5189c0749705b1e5c9f0b95e995596d8e492

Remove all known sensitive permissions in PlayApp

Change-Id: I7e9c1f665c212d9dc363ad98a010c0b5e5b96bb3