v0.7.1 Fixes scrolling while dragging and other improvements.

✅ When dragging an element, the element would interfere with the cursor's scrolling operation. Grabbed elements now use the pass through mouse filter so that the cursor can function without impedance.

✅ When dragging an element after fixing the previous issue, the drop marker would not follow the cursor when scrolling past the initial area. This is because it was using the global position when it should have been referencing the local position of the background to understand it's full position on the board, not just the viewable area.

✅ Many small improvements to the measurements between ranks and entries so dragging & dropping will feel more smooth & accurate.