Fix a crash when TDSocketChangeTracker gets an error
Fix a crash when TDSocketChangeTracker gets an error

During the -errorOccurred: method's call to [self stop], the delegate would end up releasing the tracker,
causing it to be dealloced prematurely. Moved the stop call to the end, and for safety's sake added a
temporary retain during the entire stream:handleEvent: call.
(Bug reported by Joerg Birkhold.)

myDario/couchbase-lite-ios,tomco/couchbase-lite-ios,brendand/couchbase-lite-ios,macoscope/couchbase-lite-ios,brendand/couchbase-lite-ios,ryuzmukhametov/couchbase-lite-ios,lordkev/couchbase-lite-ios,gotmyjobs/couchbase-lite-ios,Chavenay/couchbase-lite-ios,brendand/couchbase-lite-ios,Chavenay/couchbase-lite-ios,alfared/couchbase-lite-ios,ipmobiletech/couchbase-lite-ios,amco/couchbase-lite-ios,pellekrogholt/couchbase-lite-ios,evsukov89/couchbase-lite-ios,amco/couchbase-lite-ios,pellekrogholt/couchbase-lite-ios,couchbase/couchbase-lite-ios,amco/couchbase-lite-ios,pegli/couchbase-lite-ios,brendand/couchbase-lite-ios,macoscope/couchbase-lite-ios,macoscope/couchbase-lite-ios,couchbase/couchbase-lite-ios,alfared/couchbase-lite-ios,mz2/couchbase-lite-ios,gotmyjobs/couchbase-lite-ios,amco/couchbase-lite-ios,pellekrogholt/couchbase-lite-ios,mz2/couchbase-lite-ios,amco/couchbase-lite-ios,couchbase/couchbase-lite-ios,ipmobiletech/couchbase-lite-ios,ryuzmukhametov/couchbase-lite-ios,myDario/couchbase-lite-ios,lordkev/couchbase-lite-ios,couchbase/couchbase-lite-ios,jkingyens/couchbase-lite-ios,evsukov89/couchbase-lite-ios,brendand/couchbase-lite-ios,ryuzmukhametov/couchbase-lite-ios,lordkev/couchbase-lite-ios,pellekrogholt/couchbase-lite-ios,amco/couchbase-lite-ios,tomco/couchbase-lite-ios,gotmyjobs/couchbase-lite-ios,lordkev/couchbase-lite-ios,Chavenay/couchbase-lite-ios,pegli/couchbase-lite-ios,amco/couchbase-lite-ios,tomco/couchbase-lite-ios,couchbase/couchbase-lite-ios,pegli/couchbase-lite-ios,mz2/couchbase-lite-ios,macoscope/couchbase-lite-ios,jkingyens/couchbase-lite-ios,pegli/couchbase-lite-ios,gotmyjobs/couchbase-lite-ios,jkingyens/couchbase-lite-ios,alfared/couchbase-lite-ios,myDario/couchbase-lite-ios,jkingyens/couchbase-lite-ios,ryuzmukhametov/couchbase-lite-ios,evsukov89/couchbase-lite-ios,ipmobiletech/couchbase-lite-ios,tomco/couchbase-lite-ios,couchbase/couchbase-lite-ios,ipmobiletech/couchbase-lite-ios,alfared/couchbase-lite-ios