Fix #845: Add Clear button and alter layout of backend edit attachments view (Event + Venue)
Merge remote-tracking branch 'remotes/origin/development' into dev21
backend: Change 'filter' to 'filter_type' (#842)
backend: if searching by category show all categories of resulting events
Alter backend css to get it more acceptable on Isis template,
also set package version to 2.1-dev002