Review changes in Gramps 5.2

[DavidMStraub]

As mentioned in #424, a couple of changes in Gramps 5.2 need review to see if we can add a corresponding feature or can simplify our code:

• [ ] Add support for open spans.
• [ ] Add strikethrough and superscript/subscript support.
• [ ] Add new gender option of "Other".
• [ ] Add citations to event references.
• [ ] Add coordinates format with description. Fixes #11248
• [ ] Remove the note type 'Html code' for notes. Fixes #12184
• [ ] Add a new person filter rule 'HasAddressText'.
• [ ] Add 'HasAttribute' filter rule to repositories, sources and
• [ ] citations. Fixes #9845
• [ ] Add new note type of "Analysis".
• [ ] Add Stillbirth as pre-defined event type. Add Stillbirth as a
• [ ] fallback for both Birth and Death events.
• [ ] Change "death cause" to "cause of death".
• [ ] Add Godparent as event role.
• [ ] Replace TEMP_DIR by tempfile object.
• [ ] Fix Place.get_text_data_child_list
• [ ] Note LINK support for merge of other objects.
• [ ] Note LINK support for deletes of other objects.
• [ ] Support Note LINKS as backlinks.
• [ ] Do not strip checksum of media object in private proxy.