(GH-2) Added test for Blame::Cache.
(GH-2) Added Plugin::Blame::Cache->new().
(GH-2) Added Plugin::Blame::Cache->get_repository().
(GH-2) Added Plugin::Blame::Cache->get_blame_lines().
(GH-2) Added Plugin::Blame::Cache->set_blame_lines().
(GH-2) Added cache support to blame().
(GH-2) Test new optional cache support.
(GH-2) Added new prerequisites.
(GH-2) Synchronized meta files.