Update manager.php

add caching to getUserGroupIds
Update manager.php

added description and blank lines in getUserGroupIds
Update manager.php

defined $uid in getUserGroupIds
Update manager.php
Update manager.php
Update manager.php
clean up function getUserGroupIds

clean up of function getUserGroupIds and improved caching mechanism of cachedUserGroupIds
modified caching mechanism in getUserGroupIds

removed cachedUserGroupIds, instead changed indexing in getUserGroups to groupId
adapted tests for a groupId indexed group array
fix in displayNamesInGroup: when specified limit N, we did complex search only in the first N users
Update adapter.php

Modified insertIfNotExist() to support NULL values
add unit test
Also update sqliteadapter
Fix use Sharing Api with calendar

Without this fix it logs this error:
Undefined index: itemSourceName at /opt/local/apache2/htdocs/oc7/core/ajax/share.php#44
I think the itemSourceName is only used with sharing files!
fix orientation in image-backend, not in preview system itself
Remove special case for css in OC.filePath
add utf8 folder test
Fixed file list sorting

Now using a natural sort algorithm that is more consistent between JS
and PHP (although not perfect in some corner cases)

- added OC.Util.naturalSortComparator that uses the same algo that was
  used for the user list
- changed user list and files list to use OC.Util.naturalSortComparator
- removed toLowerCase() and changed the comparator to use
  String.localeCompare()
- added unit tests
- added OC_NaturalSort that is used by OCP\Util::naturalSortCompare()
Fixed sort algo for additional cases
improve logo flexibility to fix wide custom logo alignment, fix #9339