Fix gwpy-plot: --title arg, q-xfrm time res, length of data fecthed, labeling updated

Created by: areeda

Addresses issue #995 (closed) redo several commits/merge to clean logs. title, q-transform data retrieval, time res, labeling:

gwpy/cli/cliproduct.py: titles are one line only, latex escapes only if needed

gwpy/cli/qtransform.py: time resolution (tres) set from output image resolution and data duration length of data read determined by plotting duration + pad for filter settling data analyzed determined by what is plotted. Multiple plotting times vary a lot Labeling includes time resolution, general formatting for some numbers, and removing closing square brackets