Fix URL pointer to Help page for sensor components

Change-Id: I658540a00dc760c514a080071c7bf5128bce50e9
Only permit one session per user

Only permit one session per user. Newer sessions cause older sessions
to become read-only. Enforcement is controlled by a flag in
AppInventorFeatures.

Change-Id: Ie493b6477473dc8d9377690a044a9fa012e2f27c
have basic functionality that prompts user on delete if descendants are greater than 3, also converted tabs to spaces

Change-Id: I42fd91c8a4c5866ed3f0273e14b680aca872bf1d
No longer show the “red bar” for stale sessions. Use Dialog Instead.

Display a Dialog box offering to reload the current session or end
it. Ending it replaces the window contents with a message saying the
session is ended.

Change-Id: I185089410ba46f67fc03aaa00eb54f532a679c18
Restore missing Sound component documentation

Change-Id: I617d009e4d0ac8ff1a42229c3bea52a3a4338d2c
Lockout Project and Screen Switching during I/O

Change-Id: I5bb05eb97bc10737abebf3b17014d81cef6a4ed9
Update Wording in the Multiple-Session Dialog Warning.

Make the dialog people see when they are logged in from more then one
location more user friendly. Also fix the forums link from the Help
menu to go directly to Google Groups instead of via the Website. This
is a work around for a Google problem (problems uploading images in
replys).

Change-Id: I66f6c3311fe5fc339d1ead2d11bc1498ef743e82
Merge branch 'privacyinformer'

Conflicts:
	appinventor/appengine/src/com/google/appinventor/client/Ode.java
incorporated Jena