* Implement Redi scheme and GM scheme.
* Modify some descriptions for the numerical experiments of density-constant and density-variable ocean circulation on a Aquaplanet.

commit e83877e2dc5d66de87d00d2040446d6955e70d70
Author: Yuta Kawai <ykawai@gfd-dennou.org>
Date:   Mon Nov 17 13:27:13 2014 +0900

    * Implement two mixing scheme for eddy miximg by the sub-grid scale geostrophic eddy, which are Redi scheme and GM scheme.

commit 46aef276822e1c845c2e4327aa2fd81bbbdcf835
Author: Yuta Kawai <ykawai@gfd-dennou.org>
Date:   Mon Nov 17 13:24:12 2014 +0900

    * Commit for Kawai work.
    * Add a formulation of density-variable ocean circulation on an aquaplanet.