fixed resizing mediamanager panels in Chrome using browser sniffing (FS#2351) - any better solution welcome

Changes to plugins cascade for FS#2359

renamed plugins.protected.php to plugins.required.php and added it cascade to allow overwriting as a local protected file

pt: paraphrased '<' character in some language files to avoid XML errors

as per commit 34bc7405

paraphrased '<' character in some language files (en, de, de-informal) to avoid XML errors -- please fix other languages

re-added font-size to .ui-widget of jqueryui theme to make programmatical removing of font-family easier

fix widths of panels in fullscreen mediamanager to be 100% when resizing (FS#2351) -- please test in different screen sizes, etc

This fixes password changing operations: password change and user
modification are two different operations on the AD backend - the user
modification should not be done on password only changes.

Now params_toarray() correctly decodes parameters on parsing query
strings

From the release notes: This release fixes a few bugs, including a major URL
parsing bug, where URLs with query strings were parsed incorrectly.

This makes the security token more robust agains session fixation
attacks. A CSRF warning will no longer abort a page save but lead to the
preview mode to avoid information loss when a user logs in during
editing (eg in another tab).

show accesskey also on actionlink title and add accesskey parameter only if a key is defined (FS#2226)