Previewing a lines output makes memory use balloon

[SamCarlberg]

This is caused by tens of thousands of Pointer$NativeDeallocator being created every second (~30k-40k) because two new points are being created for every line. Each point has a deallocator object, so this results in a ton of useless objects.

Resolution

Reuse a single Point object and modify it's coordinates before drawing the line endpoints

Note: this will need to be fixed for the next release