Changed the Method 'save' of the literature dbobject. The ref counter of the old entry gets now decreased.
Had to split the function save to a second function edit. Save only saves the object. Edit checks if there are refs and so on.
Implemented the edit form. Logic coming soon.
Added edit form for literature entries in a course. Logic isn't fully functional. The coverpath isn't supported (cover will be deleted) and there is no possibility to add a new link.
Editing is now functional. Except: Coverpath, Adding new link fields. Also fixed some ref bugs in the duplication/save function.
Added a gitignore file that whitelists only the plugins.
Merge branch 'master' into edit-entries

Conflicts:
	.gitignore
In der SRU Suche wurde ein Namespace geändert. Dieser wurde angepasst.
In der SRU Suche wurde ein Namespace geändert. Dieser wurde angepasst.
Merge branch 'master' of https://github.com/streldev/moodle-literature
Replaced some hardcoded DIR_SEPERATORS with the PHP Constant DIRECTORY_SEPERATOR. There was an error including the enricher settings.
Fixed capitalization of the pluginname
Fixed a typo in the constructor. associateTag -> associatetage
Fixed some reference bugs in the lang files
Changed a litle typo in the code
Fixed some issues with literature im-/export

Import was actualy broken. To get ride off a lot of file code, i
simplified the file upload. Replaced the filemanager with a filepicker.
From now on its only possible to upload one file after another.

Also changed the extension format for converters from ".extension" to
"extension". Its all about the DOT! ;-)
Refactored the session properties. No stdClasses any more. Its too dangerous to bould an hierarchy with stdClass
Cleaned up some session code. Was useless after refactoring.
Fixed serious xss bug in the literature_view_full function
Fixed xss vector in literature_view_list function. See also last commit.