JMAP support #134
Description
Not high priority but when good JMAP Calendar clients appear I want rustical to support the spec too.
Needs some thoughts about how to store data. Might be useful to store calendar data in json instead of ical anyway, for example because sqlite offers some methods to directly work with json data.
Some benchmarking would also be interesting to see how parsing speed differs between json and ical and what the conversion overhead is.