Wip sip23 √

The map is removed from the TL at the end of each execute method.

The EC holds a reference to the map, so while the EC is live the map's
"locals" will remain live. I think that's pretty sensible behaviour. Or do
you think something cleverer is needed?

Maybe before you review that code too closely lets see what @mariusaeriksen
<https://github.com/mariusaeriksen> thinks about the idea. :)