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

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.

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)

unset does not reset the Array's internal pointer which messes up later
calls. array_pop is still much faster than array_splice

Looks like a for loop is faster than array_splice

The file contained a few DOS lineendings and trailing spaces

Turned out a test wasn't really testing what it should have been testing
and thus did hide a bug. Still puzzles me why it still worked some
times.
This patch also sets the default iteration count for bmd5 and pmd5 to 8.

When an overlong edit summary was given for an edit, the resulting
changelog line could be longer than the chunk that is handled in the
changelog reader (8192 bytes) causing the reader to abort the operation.

This meant that old revisions where no longer accessible. This patch
fixes the reader (it continues reading chunks until a full line is
found).

However, limiting the summary makes sense and will be added in another
patch.