[releng] xtext maintenance urls for nightly and stable 

Change-Id: I834412ce81708ade701a186ab150ca9afd9f5225
[418915] Avoid  problem with external rehasher with safer logic

Change-Id: I44f4d0907153041723fd06b548e244ecfbdfd7ee
[417667] Don't resolve the container when asked not to do so
[419115] Ensure that "this" and "super" are declared as visible

Change-Id: I38ac88991ad195932630db9e1e88cd69057458c2
[417667] Also increment the versions

Change-Id: I6ca4eb43132fdc02c48db8788815d4b01201f3c0