Get rid of code reloading issues by not caching

Caching source code lines makes code reloading complicated and error
prone, and I don't think we need it performance-wise. This makes the
"reload" command and the "autoreload" setting unnecessary so I'm
removing them.
Bring CHANGELOG up to date

This is the last time I do this. From now on, CHANGELOG will be curated
and updated frequently.