itacac: Replaced last_gap and adjust_window properties on itacacpad with samples_available_for_padding

gstlal_itacac.c: fix bug where you try to flush more samples than we have from an adapter in a corner case

dropping coinc function

2 gstlal_peak_state structs per sinkpad. Also rearranged logic a bit, so
nongaps are now copied and sorted for all 3 detectors before any triggers are
generated

compute chisq for the first sample in a trigger window, itacac will now try to
save enough samples to form a coincidence with something in the next window.
The bookkeeping is 'done', though it's probably got bugs. This version of
itacac will also probably still not compile. It's got some coincidence stuff in
it, but the coincidence stuff isn't complete

gstlal_peak_state structs. Not sure if this plumbing will be used, but
committing it so that we wont lose it. Note that itacac will not work at all in
this commit, probably wont even compile

lines from header file. Added logic using a local copy of struct
gstlal_peak_state with includes a new boolean called no_peaks_past_threshold,
meant to be a temporary hack to inform python layer of times when a trigger
could exist for an IFO but none do

Makefiles are not configured to build itacac, and it will not work
without a patch for gstlal_snglinspiral that will be pushed yet