fix #644
fix #645
remove doc_files folder

Easier than trying to keep it current. Besides the information is all
available elsewhere
protect against unauthorized script insertion

Fixes sanitization when TinyMCE was not enabled. Also removes script
elements from TinyMCE edited fields. So at this point only codeblocks
may contain dangerous elements. So there is a new user right that
controls who can edit a codeblock.
Merge pull request #646 from zenphoto/1.4.6

Dutch translation