* Implement a module which provides the interfaces for various types of EOS.

commit 66e067bb71fae26b482fe113533bca1126a9bee2
Author: Yuta Kawai <ykawai@gfd-dennou.org>
Date:   Fri Dec 6 11:28:32 2013 +0900

    * Replace the hard-code for a linear EOS with the code in which calls each EOS  routine via EOS driver.

commit 5633241eb1133b346732565747addeedc61e19d1
Author: Yuta Kawai <ykawai@gfd-dennou.org>
Date:   Thu Dec 5 23:54:15 2013 +0900

    Recommit to add a EOS driver module which was forgot in the previous commit.

commit 223f665f7c8e528e4531437148a898614b144c6b
Author: Yuta Kawai <ykawai@gfd-dennou.org>
Date:   Thu Dec 5 23:46:29 2013 +0900

    Implement a driver module for each EOS module and add some physical constants.

commit ce8e34f4eea869c89c089fc2a1ff805291012293
Author: Yuta Kawai <ykawai@gfd-dennou.org>
Date:   Thu Dec 5 17:07:49 2013 +0900

    * Add a module for a linear EOS.

commit 7ceff9f777472283df250db3fc445198a1d84fa2
Author: Yuta Kawai <ykawai@gfd-dennou.org>
Date:   Sun Dec 1 16:51:39 2013 +0900

    * Create a driver module for EOS.