updated NEWS
added 'OLD_' prefix in front of old solvers
keep skolems as is -- otherwise this breaks proof steps that refer to variables that were 'obtain'ed in the outer Isar proof
minor NEWS fix
moved new para to right section of NEWS
tuned terminology
intern xthm only once;
more liberal embedded "text", which includes cartouches;
tuned;
three-line 'obtain' format for generated Isar proofs
tuned method description
added 'skolem' method, esp. for 'obtain's generated from Z3 proofs
moved skolem method
going back to bc06471cb7b7 for silencing -- the bad side effects occurred only with 'smt', and the alternative silencing sometimes broke 'auto' etc.
tuned tracing output (indirectly)
try 'skolem' method first for Z3
took out one more occurrence of 'PolyML.makestring'
made trace more informative when minimization is enabled
tuned message
show microseconds as well (useful when playing with Isar proofs)