check and build Isabelle session for console tool -- avoid multiple Scala/JVM invocation;
#!/usr/bin/env bash
#
# Author: Makarius
#
# DESCRIPTION: invoke Scala within the Isabelle environment
isabelle_admin_build jars || exit $?
isabelle_scala scala -Dfile.encoding=UTF-8 \
-classpath "$(jvmpath "$ISABELLE_CLASSPATH")" "$@"