[isabelle-dev] ProofGeneral-4.2

[Makarius]

See d3ee6315ca22, which is just a pro-forma update of the Isabelle 
component, it is also made the default for bundling in the next release. 
(David Aspinall actually suggested to stop the bundling altogether.)


Sorting out the old PG 4 settings problem on the Isabelle side recently, I 
had to start PG several times, and I still do that in rare situations to 
try something out.  I can't say if it actually works in practice, if put 
under stress.

So this is just the normal catch-up with the official PG train, without 
any special efforts that I did in the past.


 	Makarius