Add support for RIFT to the model module

[cdcapano]

What the subject says.

[oshaughn]

Based on lalsimutils.py, factored_likelihood.py in RIFT repo

• Define twosided complex timeseries in pycbc; see devel branch and pull request
  • Add tool to 'promote' onesided frequency series to twosided.
• Variant of matchedfilter.py (matchedfiltertwosided.py) to provide review-safe, modular twosided inner products. Needs
  • Two sided PSD creation
• Access to hlm(t). Practice inner products on hlm in complex form.
  • Tool to compute standard inner product matrix.
• gwin class for gaussian_likelihood_rapidpe
  • Define class (subclass of base_data class) class. Reformat data to two-sided.
  • Waveform generation hlm. Implement argument caching as needed
  • Construct U, V for all detectors.