#26 Mjc should report all errors, instead of one at a time

[Gary T. Leavens]

It would be nice if, whenever semantic error recovery is
possible, mjc would continue processing so that more
errors could be reported in each run. This would be
more convenient for users.

On the JML side we have made it so there is a try block
around clauses that catches the exception, reports it,
and then continues. This kind of thing could be done in
mjc also.

We're closing JML RFE 663570, which was reported by a
user, in favor of this.