Merge the following from the enterprise branch into the enterprise35.0.20100305.1099257 tag: SVN_MERGE

SVN commit 1101903 by tmcguire:

Detach the observers before deleting the mementos, otherwise deleting the mementos will
trigger and update of the readerwin, which will crash, since the memento map is in an invalid state.

kolab/issue4187
MERGE: trunk (afaik it is done with signals/slots there, needs to be adapted)

svn path=/tags/kdepim/enterprise35.0.20100305.1099257/kdepim/; revision=1101905