[DrJava] friendlier (and more correct) Test functionality

[Eric E. A. <ea...@cs...>]

I just committed a whole slew of bug fixes that should make the Test
button functionality much more user friendly. In particular, I'm pretty
sure that I've caught all the ways in which the Test button code could
cause DrJava to hang.

BTW, Let me reiterate my message from Friday: If an UnexpectedException is
thrown, it should mean that a bug was found in DrJava. Don't throw them in
any other case. If you do, you may cause DrJava to freeze completely, as
if it were some sort of crappy C++ application.

-- Eric