Allow to create MediaSpecimen when creating specimen for a type designation
When creating a new specimen (unit) for a type designation one may currently only create a PreservedSpecimen. This should be changed by also allowing to create MediaSpecimen as sometimes (and in some taxonomic groups often) type specimen are media e.g. an image in a book.
An example for a media lectotype from Cactaceae:
Lectotype: [illustration] photograph accompanying the description of the species in Kakteenkunde 1934: 177. 1934