PhenoPacket.java should go under model

[cmungall]

I like the prominence, but it feels disconnected from the rest of the model stuff, seems to break modularity

I think in here:
http://www.javadoc.io/doc/org.phenopackets/phenopackets-api

clicking on the model package should have Phenopacket as the main class

For the top-top level package, perhaps a general purpose utility class?

thoughts @julesjacobsen ?

[julesjacobsen]

Logically it makes sense to put it under model. Originally I put it at the top level in order that there was no cross-talk between the model and io packages. Nothing in model refers to PhenoPacket at all, but both the Yaml and JsonReader refer to PhenoPacket. I'm happy either way.