Ucspec addition

I was experimenting with ucunit and a more behavior-driven approach to testing. Here's the result, in the hope it might be useful.

By default, it needs to have UCUNIT_MODE_VERBOSE undefined, so I moved that to Testsuite.c.

Optionally, it can have UCUNIT_MODE_SILENT defined, which will suppress failure details. 

When used in this way, the test output very nicely documents the specifications that were thus tested.

It is also possible to add empty specifications (without test code). These will be flagged as NOT IMPLEMENTED.