add spiraling effects to nomads black hole suck in code

currently the nomads black hole features code that allows it to suck in units that it kills. right now the effect is pretty simple, with all units being sucked in directly. the black hole effect should instead make them spiral into the centre.

bonus points for making the speed different for different units.

Start by locating the Nomads black hole suck-in code and inspect how units are currently moved directly toward its centre. Done means affected units visibly spiral into the centre instead, with different movement speeds for different units if the bonus is included.

Written by the indexing model from the issue text.