[PATCH] lib: Bump SO version from 2.0.0 to 3.0.0

[David Bremner]

Austin Clements <amdragon at MIT.EDU> writes:

> We've changed the APIs of notmuch_database_open,
> notmuch_database_create, and notmuch_database_close.

pushed an amended version. But you know all about that.

d