Accepted some patches from the Multicore Programming Group at Imperial College London...

Accepted some patches from the Multicore Programming Group at Imperial College London (via Peter Collingbourne):

cvc4-0001-Look-for-cxxtestgen-as-well-as-cxxtestgen.pl-and-cxx.patch
* better checking for cxxtest
cvc4-0002-Do-not-read-an-additional-command-after-failure.patch
* more correct failure behavior for interactive tools
cvc4-0003-Only-exit-when-encountering-a-CommandFailure.patch
* don't consider "unsupported" as a failure (accepted with modifications)
cvc4-0004-Produce-SMT-LIB-v2-conformant-output-for-get-info.patch
* better get-info responses (accepted with modifications)

These patches will help the group build Boogie support for CVC4.

(this commit was certified error- and warning-free by the test-and-commit script.)