PORT-72: Updates to the build system to support the automatic generation
of release and debug libraries on linux. This includes changes to the
CppTask dependency and will require a retest on Windows. I have updated
the windows build file, but haven't tested.

At the moment, all compile tasks just build both release and debug, and
the testing targets only use the "release" libraries. Will need to
change this over so that the tests use debug libraries. Will also have
to think about whether or not the default builds just build debug
libraries (rather than both release and debug) and build release
libraries only when building a real release. Food for thought, but I
suspect the small additional compile hit is a small price to pay for
simplicity here.