Set model only if no model is set

e.g. if a web wants to store newsletter subscriptions as a backup
Fix afterDuplicate to support events as well
Check additional Roles only when there exist some
Remove readfile_chunked again

Causes Problem with some servers
Add _allowFrontendUrls() to User Row
Use correct variables
E-Mail is case insensitive

Fixes that a user already exists error occurs when changing e-mail adress to upper or lower case
Check if Image really is uploaded
Implement hasContent for switchLanguage-Component
added jQuery Plugin Transit with Fallback

makes it easy to animate elements with css3 transitions and if this is not supported it fallbacks to jQuery animate
added jquery easing plugin

for custom easing effects in jquery
Merge remote-tracking branch 'upstream/3.3'