ProB 2 now always throws ProBError for parse errors and
ModelTranslationError is no longer used.

https://jfrog.com/blog/into-the-sunset-bintray-jcenter-gocenter-and-chartcenter/

The Gradle documentation says that these convention properties are
deprecated and superseded by the java and application extension blocks.
Using the convention properties doesn't generate warnings yet, but it
can't hurt to switch to the now recommended way.

This doesn't affect predicates passed to :exec/:constants/:init yet,
because ProB 2's StateSpace.transitionFromPredicate method currently
only accepts a string predicate (which is parsed using the model's
languate) and not an arbitrary IEvalElement.

This fixes a bug where interrupting a command would terminate the main
event loop thread, causing the kernel to stop responding. This happened
because the interrupt handling sent a Java interrupt to the thread
executing the current command, which was always the main event loop
thread. Now commands are executed on a separate executor, which can
safely have Java interrupts sent to it without affecting any
jupyter-jvm-basekernel threads.

When an error points to an external file, its source code is now read
and errors highlighted in it.

Error highlighting for code from the last load cell now also works when
an error pointing to it is thrown in a later cell (although this
doesn't happen often). The initial/default machine is also recognized
(although there should never be errors pointing to its code).

At the moment error highlighting is only supported for the
machine/formula in the current cell.

This significantly improves the performance of loading new machines.