Adds hotkeys to zoom without limits in either direction*.

Default hotkeys are 'CTRL + K' and 'CTRL + L'

For additional info please see the forum post https://forums.factorio.com/viewtopic.php?f=92&t=42519

Please keep the bug reports in the forum post as well.

Thank you, enjoy.

*Had to add some limits as the game starts behaving strangely once you push it far enough.