added support for schema changes - schema can now change and dapper will re-generate the deserializers.

EG:

  DynamicParameters p = new DynamicParameters();
  p.AddDynamicParams(new { A = 1, B = 2 });
  p.AddDynamicParams(new { C = 3, D = 4 });

Expose some more of dapper's internals

added test for TVP

standardise perf tests on First(); measure buffered and unbuffered (dapper only); introduce * splits, useful for creating tuples of primitives

changed multi mapper sig, it makes more sense to define a return type that way you can return an aggregate object more naturally