Deprecate tags

because tag is not common to media
so, the tag class will be supported by the media need this class
tag will be removed from ver.2.
Implement a reference system
Remove an unused property
Remove codes using a table of contents
Remove a class for contents table
Unsupport a class for tags
Remove a test file for a table of contents
Remove unsupported classes
Remove unefficient codes
Update a version identifier