use multible approvers

the plugin now requires a given number of approvers
to show a document as approved.
handle multiple users in revisions
removed recent.php
removed approve button from edit form
adjusted redirect to latest approved revision
changed get revision
added approval table
Merge branch 'master' into multiple_users
spelling fix
spelling fixes
wording fix
spelling fixes
set default approver count to 1
added approval colors to recent changes
approve action now leads to correct revision
added phpdoc comments
plugin now converts old meta data format to new
added option to hide drafts from read-only users
added publish event
hide banner on hide drafts