In OpAddAnnotation support annotated ranges with 0 length

[kossebau]

ODF has the concept of annotations with and without a range (either there is an <annotation-end> element or not). One could argue that an annotation with a range 0 (thus no content between start tag and end tag) has the same semantics as an annotation without an end tag.

Just, as a matter of fact currently the editing ops make a difference between both. And currently it is also not supported to change an annotation to be either range-less or ranged. So when removing all content between start and end tag, an annotation still stays ranged.
Ideally that would get a proper solution one day...

In the meantime, while pondering with OT for the annotation ops, I found it would be needed to have the AddAnnotation op to also support annotated ranges of length 0, and not just to assume a parameter of length=0 means unranged annotation.

So it makes the op match the full set of possibilities with ranged annotations. And it helps with OT for annotation ops :)

Non-backward compatible spec change (due to change of meaning of length=0).

[kogmbh-ci]

Build succeeded.
Refer to this link for build results: http://ci.kogmbh.com/jenkins/job/WebODF-PullReq/2344/

[peitschie]

Usual terminology for this is a "breaking change" (in case you weren't aware)

[kossebau]

Never heard before, thanks for the hint. Suspect that is MS lingo, so that could be why ;)
Still, seems it is quite in use and also a short term, so happy to use it.
Hm, wondering if that should be a separate section even, and not just a inline comment. Guess it should.

[peitschie]

A simple enough change... makes good sense to me. Please or 🚀 if you prefer!

[kogmbh-ci]

Build succeeded.
Refer to this link for build results: http://ci.kogmbh.com/jenkins/job/WebODF-PullReq/2345/

[kossebau]

🍪s for the review, @peitschie Hm, out of rockets, so taking the 🚢