[isabelle-dev] NEWS: system option pide_session is enabled by default

[Makarius]

*** System ***

* System option "pide_session" is enabled by default, notably for
standard "isabelle build": this allows to invoke Isabelle/Scala
operations from Isabelle/ML.

This refers to Isabelle/026de3424c39. It is practically relevant for
Isabelle/Scala functions in Isabelle/ML.

It is still possible to opt-out, e.g. like this "isabelle build -o
pide_session=false", but at a later stage non-PIDE batch builds will be
discontinued.


	Makarius