gstlal_inspiral, inspiral.py: make process start time the same for each output file for accuracy and to reduce process metadata bloat

injection str at end for use in analysis makefile will now be written to a user
specified file instead of to stdout

this fixes the code (for some unknown reasons) falsely adding (some of the) GAP segments in the analyzed segment list
there is still a bug where segment of length 0 gets included in the segment table, but it won't affect the livetime

to save memory

for obtaining the segments analyzed

gstlal_feature_extractor_pipe: determine drop time based on fft length, split up combiner jobs into disjoint gps ranges

gstlal_feature_combiner: allow saving features to a separate directory, optionally pass in start, end times

utils.py: when saving features, only store time-based columns as double-precision, rest as single-precision

appears fix the issue people are having with injection jobs
occasionally hanging

Fixing sanity checking & remove unuse option

outputting SNRs