Feature/ae split generators and algorithms

To repeat what I said in issue #167:

 - for all the algorithms the pedestal is retrieved from the SQLite database that is produced by ```PlotPedestalsAndNoises```. If you don't have the SQLite database locally, then you can create one by running rootana with this module and setting ```export_sql=1``` in your modules file.

 - the various pedestal/trigger polarity/etc. variables should be assigned in the generator and not the algorithm so that we don't get a massive slow-down. I would quite like a way to check that these variables exist before running the algorithm (i.e. fail loudly) but can't think of a way to do it

Could people please check that I haven't either:
 - broken an algorithm while copying it over, or
 - done something dangerously/inefficiently/badly

Cheers
I thought ```GetSamples()``` did this now. I've been doing this:

```
const std::vector<int>& samples = tpi->GetSamples()
```

would this not work then?