Select on full noise

This patch adds an AttributeTransformation that generates realizations of the full (complex) noise vector in each detector and estimates observed SNRs directly from that and the waveform. Selection can then be done on observed SNR via a conditional within an EventGenerator.

The patch also expands the logic for how event parameters are written to disk to include vectors instead of just scalars.

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changes

• updated parser to automatically detect and create gw-detectors Network objects
• added distributions.noise module, specifically StationaryGaussianComplexFrequencyNoise
• added the concept of scalar and vector variates to allow for better control of memory usage and how data is written to disk
  • each distribution, transform, and event generator declares both _scalar_variates and _vector_variates. These are concatenated when one asks for variates
  • event generators know how to delete all vector variates from events during sampling in order to help with memory consumption
  • gwdio knows how to write vectors to HDFiles in addition to the scalars
• updated some logic within naming to allow for better tests with random naming conventions
• added new test scripts, particularly focusing on the workflow from noise , waveform -> projected strain -> optimal snr, observed snr
• lots of misc debugging

this patch goes along with this merge request in gw-detectors.