Fixed threadpool hang and added lots of smoketests. * Fixed bug in threadpool logic when calling CleanupAnyWorkersSharingAllocator - this was deleting the worker's thread death notifier in the context of a worker thread (which is only allowed from the context of the main thread). * Added lots more smoketests * Added --overwrite option to fzip (previously unzipping would always overwrite)

---------------------------- Test U1 ------------------------------
1:X one
2:X two3:X three4:X four
5:X five
6:X six
7:X seven…8:X eight
9:X nine
10:X ten
---------------------------- Test U2 ------------------------------
12-Before 111
13-Before 222
14-Before 333…15:Match
16-After 111
17-After 222
18-After 333