Hall A Analyzer

The ROOT file output handler, THaOutput, is not well written and quite limited in some ways (although nice in others). I'd like to do the following:

1. Make the class a plugin. This is needed for multithreading. It will also allow us to write results to other file types. Podd's output is n-tuple-like, so we may speed things up greatly by avoiding the complex TTree structure. Maybe …
2. Support the full range of data types. Currently, all data in the TTree branches are converted to double. Inefficient and leading to loss of precision in some cases.

I have already done quite a bit of work on item 2, but that code needs to be recovered from old private branches.