doc of save_markers
Added documentation
raise exception if no active event marker is set
Todo: call snuffling when 's' pressed.
removed unused import of util.reuse
Revert "Merge branch 'master' of github.com:HerrMuellerluedenscheid/pyrocko into fomosto"

This reverts commit d2d9e3db1d45fc89b56ecff477e3c068f31f0370, reversing
changes made to 757e21a432f798b64d872794fcb4697f1117d155.
typo
removed s-press call snuffling test
Documentation added
extended/corrected documentation
snufflings: improved get_active_event_and_stations method

It now calls fail() when no active event has been selected and
one can now select what should happen, when station information is
missing.
docs: improved pile documentation