Update to MEI version 3.0.0

[lpugin]

When generating libmei using the latest stable version of MEI, I have an issue with the barlLine element. It used to have a @rend (in BarLineLogMixIn). It is not available any more, even though from the schema I can see it is valid. Any idea where to look at?

[ahankinson]

The version of libmei that is on the master branch was generated from MEI 2.1.1, and @rend is on the <barLine> element. See: https://github.com/DDMAL/libmei/blob/master/src/modules/shared.h#L262

I have not re-generated the source for 3.0.0 since I'm waiting for the release to be finalized. Is this the problem?

[lpugin]

I think the issue is that the rend was actually change to form.