Dependency on mysql

[ford-prefect]

It seems to me that the dependency on the mysql package is less than ideal -- the C library it wraps has a whole bunch of special requirements to deal with multi-threading that seem unsuitable to using in a language with a managed runtime.

Would it make sense to move to something else? mysql-haskell perhaps (apparently Persistent also has this option via https://hackage.haskell.org/package/persistent-mysql-haskell).