[isabelle-dev] NEWS

[Makarius]

* The default for ISABELLE_HOME_USER is now ~/.isabelle instead of the
old ~/isabelle, which was slightly non-standard and apt cause
surprises on case-insensitive file-systems, or when working with local 
copies of the Isabelle repository.

INCOMPATIBILITY, need to move existing ~/isabelle/etc,
~/isabelle/heaps, ~/isabelle/browser_info to the new place.  Special
care is required when using older releases of Isabelle.  Note that
ISABELLE_HOME_USER can be changed in Isabelle/etc/settings of any
Isabelle distribution.