Magic date day: 10+10 = 20... :-)
(a) Make server event listeners per-ScionInstance instead of
static. This allows the code to signal more server event types
than it does currently.
(b) Make the ScionInstance the event source in ScionServerEvent,
add the server as another parameter.
(c) Fix server executable change code in the HaskellEditor so that
the editor and the outline view refresh properly. Yeah!
(d) Refactor ScionCommand.runSuccessors to move the isSync
test outside of the loop. Gains a negligible amount of speed.
(e) Simplify ScionServer.processResponse: eliminate the try/catch
blocks, exit as soon as possible on error, ensure that the
command is always dequeued, even if there's a version mismatch
And update the code formatting for some consistency.