Did a lot of Removing

Database structure changes:
* completely removed _links tables
* merged the _terms_taxonomy
* removed term_group from _terms

Removed features
* tried to removed Link Manger
* deleted bookmark.php
* removed deprecated functions

Other changes
* term_taxonomy_id to term_id
* $wpdb->term_taxonomy to  $wpdb->terms
* README fixed some grammar
* robots.txt fixed empty lines