Hall A Analyzer

Implemented backward compatibility for the set of detectors in THaHRS. If no detector named "vdc" is found at Init time, define the set of old detectors (quietly avoiding duplicates). (Perhaps I should also check that this "vdc" is a THaVDC?)

This can be turned off by calling AutoStandardDetectors(false) before Init.

Also, a bugfix of sorts. If AddDetector discovers that a detector is already defined, it deletes the object passed to the call. The rationale here is that the detector object was given to the apparatus with the assumption that it will be managed by the apparatus. If the apparatus rejects it because it is already there, it should clean it up since it will never be used. This allows calls like

AddDetector( new THaMyDetector("existing_name") );

to run cleanly without memory leaks. Of course, if the user keeps a reference to the object in the caller, it would become a dangling pointer if the AddDetector calls does not succeed. But this can be detected by checking the return value. It is a bit risky - some people might have written

THaScintillator* s2m = new THaScintillator("s2m");
LHRS->AddDetector(s2m);
s2m->SetSomething(123);

But "s2m" already existing in such cases would be extremely unusual.

Perhaps we should throw an exception in such cases? After all, if a detector cannot be inserted, the analysis might not work as the user intended, and so the problem needs attention, not just be a warning. I'll leave that for later.

All this is in commit 3cf18e970826f87af064d96eb07547ef65b92fbc