added get_identifier for accordeon
all shared fields shall be configurable
use assertion instead of RuntimeError
link plugin does not invoke get_identifier
Re-using classid Media: js = ...  settings to specifiy JavaScript files
Fixed: AttributeError if image is missing
Instead of specifiying a sharable_fieldset in each Plugin, do a mapping for these special fields
removed dead code
Using my own change_form to render a JSON dictionary
Using format() instead of string concatenation
Now each input field is accessible through a unique element id
Fixed: missing media for SharableGlossaryMixin and ExtraFieldsMixin
Using a list of base_plugin's to automatically create JS plugins with ring.js
finalized linkplugin(base)
Fixed LinkPluginBase and LinkPlugin
testing with other settings