CRM-13159 enable 'membership_type' as a param on relationship get, display count of available relationships on back-office member form using this
CRM-13160 partial fix, eliminates fatal but doesn't address where there are multiple relationship type possibilities, required to avoid fatals on tests
CRM-13159 need to assign var to tpl
CRM-12869 ensure giftors email is not over-written on behalf membership
unrelated e-notice fixes
Merge pull request #1352 from eileenmcnaughton/CRM-13159

Crm 13159 plus a couple of minor fixes