Fix range markers for blueprints.

Also refactor a bit to use the same code for buildables and blueprints.
Changelog.
Avoid “too many target_locations” on startup (game.so, static init).
Fix mirrors.

The cull direction wasn't switched reliably. Also the alphaGen portal
is now replaced by alphaGen const 0, which at least makes the mirrored
view visible.
Changelog update.
Merge branch 'debian'