- use Python's own gzip support to check files

- word-wrap and edit comments, reword error messages, etc.

- move segment boundary logic from calling codes into this function

- and avoid type conversions in existing safety checks

- when initializing from a sequence, require each item to be a two-element object (e.g., the current version would accept 3-element objects and ignore the 3rd element).

gstlal_etg: fixed issue with saving last set of triggers, changed buffer time in to_trigger_file to be optional

specified for building sngltriggertable.c

gstlal_etg: fixed bug causing last set of triggers not being written, also only sets trigger start and end times if not using live data

- use gpsproperty() from lsctables instead of implementing it from scratch