In feedback state, change back to previous status

When an issue is in $g_bug_feedback_status, $g_reassign_on_feedback
is ON and the reporter adds a note, the issue's status is changed back
to what it was before being feedback, unless it was equal or greater
than $g_bug_resolved_status_threshold, in which case the status is set
to $g_bug_submit_status if the issue has a handler or
$g_bug_assigned_status status otherwise.

Fixes #4469
Align to coding guidelines and add PHPdoc for missing param
Fix whitespace
WIP: allow non-reporters to provide feedback on issues

TODO: split commit in cleanup vs function; test; bug ref

Fixes #