[TASK] Add some major goals to README
[TASK] Remove t3lib_parseHtml and t3lib_parseHtml_proc

Empty require files removed, adapted class mentions in core
to new namespaced names.
[TASK] Remove empty t3lib_frontendedit
[TASK] Remove t3lib_install and t3lib_install_sql

* t3lib_install_sql was split from t3lib_install a while ago, the
non namespaced class is now cleaned up like the rest in t3lib/
* t3lib_install was not migrated since the methods in there were
obsoleted for 6.0 with the Configuration change. It was still
mentioned in dbal at some points, for example in a Hook for old em.
This is cleaned up along the way.
[TASK] Remove empty t3lib_cli and t3lib_db and mentions
solve merge conflict