doc: re-add "update" target in "doc/locale/${LANG}/LC_MESSAGES"

Reported by cosmo0920. Thanks!!!
Use "Mroonga" form for engine name
test: follow engine name change

    ENGINE=mroonga ->
    ENGINE=Mroonga
           ^
storage: fix a bug that table specified index can't be removed

You can specify table of index by `COMMENT 'table "XXX"'`.

[groonga-dev,02677]

Reported by Naoya Murakami. Thanks!!!
Fix wrong return value

We should not use grn_rc for error code in MySQL. grn_rc should be
converted to MySQL error code.
storage: fix a bug that table specified index can't be removed

You can specify table of index by `COMMENT 'table "XXX"'`.

[groonga-dev,02677]

Reported by Naoya Murakami. Thanks!!!
Add NULL check
wrappr: make drop_index() wrapper mode ready
doc: add 4.05 release entry
doc: update po
doc: add missing anchor
doc: fix typo
doc: update po
doc: translate po
Bump version

    make update-version NEW_VERSION_MAJOR=4 NEW_VERSION_MINOR=0 NEW_VERSION_MICRO=5
Update target files
Update the latest release

     make update-latest-release OLD_RELEASE=4.04 OLD_RELEASE_DATE=2014-07-29 NEW_RELEASE_DATE=2014-08-29
package centos mysql55: update package version
package fedora: update package version
package yum: use the latest version