added shortcuts stt and tts for str_to_time and time_to_str
gf: fixed issues with source origin time, added test
snuffler: fixed problems with reloading of files
removing an unused variable
changed MultiplyResponse so that it can take more than two responses
snuffling: added web_frame method
serial_hamster: improved an error message
snuffler: shortened polling interval for SEP serial line reader
Merge branch 'master' of ../pyrocko-master into cdatacube
datacube: backjump capability