Merge pull request #386 from kwanggithub/master

update README.
Merge pull request #387 from kwanggithub/master

update README.
Merge pull request #388 from kwanggithub/master

update README.
Make log more detailed

When loading of the module of dependence is unsuccessful,
the name of the module of the cause is recorded on a log.
Merge pull request #389 from iSatoshiKobayashi/make-log-more-detailed

Include the module name in error message when loading module