Mimetypes Registry for DMS

just few mimetypes are supported for content indexing.
adding a new extension consists in customizing the document addon because mimetype/converter association is hardcoded there.

we can implement a sort of registry where users can specify the proper converter for every type they need to index its content.
Doing this, we can choose different tools depending of the OS for example.

The same approach is in use by others frameworks.

i can take care of this and make some proposals