gstlal_compute_strain:  Wait for good h(t) before computing transfer functions between it and witness channels

gstlal_compute_strain:  added ability to process witness channels separately for noise subtraction, if desired.

 - bug fixes in lal_adaptivefirfilt
 - Implemented lal_adaptivefirfilt to correct for f_s and Q time-dependence
 - Added options to correct for complex kappas
 - Added EPICS bits to calib state vector

gstlal_compute_strain:  Modified smoothing of f_s and Q to produce better results. Began updating CALIB_STATE_VECTOR for O3.

lal_lpfilter:  new element that takes complex input representing amplitude and phase error of a signal at a particular frequency and computes a linear-phase FIR filter to correct this error.

gstlal_compute_strain:  Use creal instead of splitting into real and imaginary parts and fakesinking (saves computational cost)

gstlal_compute_strain:  Added calibration line subtraction back in. There's also now a prototype function for subtraction of 60 Hz lines and harmonics, and for noise subtractions using witness channels.

- new package cmath: elements that perform unary operations and handle complex and real floating point arithmetic. Elements included are cabs, cexp, cln, clog, clog10, and cpow.
- new element lal_trackfrequency: base transform element that attempts to measure the loudest frequency in a signal.

- lal_smoothkappas: added filter latency option.
- lal_resample: simpler treatment of gaps. The complicated nonsense from before was unnecessary and messed things up.
- calibration_parts.py: function to remove lines and harmonics with a witness channel now works well.

- lal_complexfirbank:  Now handles latencies longer than filter length.
- lal_insertgap:  Compute offset when throwing away initial data as offset relative to the time when streaming started.
- calibration_parts.py:  remove_lines_with_witness should work now.

lal_transferfunction:  Made fir filter length independent of fft length. Added ability to resample and low-pass filter transfer functions to produce fir filters. Reduces noise in transfer functions wieh multiple witness channels are equally well correlated with the signal to be cleaned.

lal_transferfunction:  allow any length of fir filters by resampling the transfer functions. Reduce noise by low-pass filtering transfer functions.

lal_resample:  found downsampling bug that counts samples incorrectly when the first timestanp is not a multiple of the longer sampling period

lal_transferfunction:  numerous fixes to fir filter generation.  calibration_parts.py:  data cleaning function

gstlal_compute_strain:  in offline mode, apply timestamp shift to the kappas to compute them in time for lock stretches

gstlal_compute_strain:  When applying f_cc updates to hoft, require good f_cc values for hoft ok. Also, require all kappas to be good values for duration of smoothing filters for hoft ok.

calibration_parts.py:  Added new function remove_lines.