Numerical Problems with `UInt` waveforms

In case you are loading a `RDWaveform` which consists of `Integers`, most filter code in `RadiationDetectorDSP` fails because it wants to return `Int` types for each sample after the filter is applied.
So far, we convert the waveforms by something like this:
``` julia
wvfs = shift_waveform.(wvfs, 0.0)
```
There should be a more elegant solution than this.

CC @fhagemann

No file, test, or entry point is named. Start by locating RDWaveform and the filter code in RadiationDetectorDSP, then reproduce the failure with an integer-valued waveform; done means the filters handle UInt waveforms without requiring shift_waveform.(wvfs, 0.0).

Written by the indexing model from the issue text.