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
make sure class file is loaded once
change logic in displayNamesInGroup and add some unit tests
add more logic in displayNamesInGroup for big user bases
DragnDrop Upload text style

The 8px margin was uggly.
Do not show exception to the end-user

Log the error instead of potentially leaking sensitive information
replace horizontal rules with whitespace
fix error message template
Fix AmazonS3 rmdir on the root
Fix amazon s3 rename overwrite
Fix copy overwrite for amazon s3