optimized preview view and added styling for devices background
deleted all stuff for previewDomain setting
added new param preview=true for all sites to show hidden paragraphs, you must be logged in for that
added redirectAction for frontend preview requests to check if logged in
frontend link in backend links to the new preview site
added frontendPreview javascript and deleted this code from preview

if preview param is set, this will be added for all links on page per javascript
is necessary for multidomain sites because iframe dom can only be edited on same url, not for others
deleted previewDomain code
renamed absolutePreviewUrl to previewUrl and url param has absolute url for multidomains
changed preview=true param to preview

is not necassary to add additional true param
renamed device names
increased preview redirect security, only intern links are allow for redirect
Merge pull request #37 from kaufmo/3.3-preview

Preview Param and Preview View in Backend