* Make LocalFolders react correctly to removal of custom (non-default)...

* Make LocalFolders react correctly to removal of custom (non-default) folders.  It is not necessary to re-fetch the entire folder structure in this case. (plus test)
* Make the local folders un-deletable via Collection::Rights.
* Add LocalFolders::root().
* Remove LocalFolders::customFolders() -> not needed until I see a good use case for this.
* Extract the folder structure fetching/rebuilding logic into a LocalFoldersBuildJob.  Makes things a bit clearer.
* Api docs.

svn path=/branches/kdepim/soc/kdepimlibs/; revision=986102