gstlal_inspiral: fix bugs related to idq

gstlal_inspiral failed at line 856, since idq_gate_threshold is not defined. I processed the user option --idq-gate-threshold the same way it is done for --ht-gate-threshold in line 490 and added its definition in the for loop at line 653.

I also solved some typos: in three location the parser was referenced as option rather than options, raising an error.

I tested (quickly) the change and the (offline) pipeline seems to run fine after the fix.