Crossport r981640 by smartins from trunk to the enterprise4 branch:

Incidence::operator== didn't worlk properly when there were attachments involved.

Fixed by implementing ListBase::operator== and Attachment::operator==.

Review: http://reviewboard.kde.org/r/821/

This was also one of the causes of bug 195734.

CCBUG: 195734
MERGE: e4

svn path=/branches/kdepim/enterprise4/kdepimlibs/; revision=982948