t3lib_install contained two logical parts in the past: A group of methods to handle localconf.php and another group to parse ext_tables.sql files and friends. The latter was already extracted to t3lib_install_sql in the past. The localconf handling is obsolete with the new LocalConfiguration.php and its new API method.The patch handles:
- Deprecate t3lib_install and change the code in a way that does not harm if still called.
- Move some methods and properties to TYPO3\CMS\Install\Installer, make the class standalone and do not extend t3lib_install anymore.