Add some kind of upper bound constant for number of labels per grid cell

[Yomguithereal]

To avoid potential time complexity issues later on, on huge graphs.

This can even be done when adding the node to the grid, not when retrieving it (and it is faster to code & more performant).

What I mean is that given some settings, some cell might end up holding an absurd amount of nodes, which defeats the purpose of even having the grid. So the max number of nodes per cells should be clamped somehow.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.