Adding a "select call result" option when ending calls

This is to ensure that the correct call result is selecte when a
call is ended.  Previously "contacted" was the default selected item
which sometimes resulted in the incorrect call result from being
selected.
Removing unneeded variables
Merge remote branch 'origin/qa' into release
Adding new qnaire::get_prev_qnaire() method
Fixing bug in productivity report

Completes were not being restricted to a single site.
Removing defunct call attempts report
Removing accidentally committed debug statements
Adding optional collection restriction to mailout required report
Tweaking titles
Adding optional collection and cohort restrictions to participant status report
Overhauling the participant status report
Fixing incorrect comment
Adding "completed" column to assignment list
Removing debug statement
Fixing minor bug (wrong setting)
Fixing bug due to change in IVR feature

An incomplete interview is now handled by an operator calling the participant
to schedule a follow-up IVR appointment.
Adding new "id only" functionality to record::get_record_list() method

It is now possible to return a list of database primary IDs instead of
active records when calling record class' get_record_list() method.
This is much faster for calls that return a large number of records.
Adding new "id only" functionality to record::select() method

It is now possible to return a list of database primary IDs instead of
active records when calling record class' select() method.
This is much faster for calls that return a large number of records.
Fixing misnamed constant
Removing reverse_withdraw operation, restricting when withdraw buttons appear

The participant/reverse_withdraw operation was a duplicate of the
participant/withdraw operation (with cancel=1) so it has been removed.
Also, the withdraw/reverse_withdraw buttons in the participant view
widget only show when there is a withdraw script available for that
participant.