Use delta rather than markers in gridpoints_in_polygon

[gpeairs]

gridpoints_in_polygon looks at one row of a grid at a time. For every polygon edge intersecting that row, it marks every grid point to the left of that edge, adding or subtracting 1 depending on the edge direction.

This just adds a delta at the first element and at the new edge, then does a prefix sum at the end. We also now avoid some other unnecessary allocations. The results are the same, verified against full designs, but we get ~3x improvement in benchmark times and huge improvement in allocations for large grids. Integration benchmarks ("coarse and fine") don't see the full speedup because they spend time on geometry construction.

Old:

ID	time	GC time	memory	allocations
["autofill", "coarse_and_fine"]	22.786 ms (5%)		41.56 MiB (1%)	381122
["autofill", "gridpoints_in_polygon", "3201x2401"]	28.507 ms (5%)		50.13 MiB (1%)	50596
["autofill", "gridpoints_in_polygon", "321x241"]	357.966 μs (5%)		683.22 KiB (1%)	4708
["autofill", "gridpoints_in_polygon", "33x25"]	22.950 μs (5%)		38.23 KiB (1%)	641

New:

ID	time	GC time	memory	allocations
["autofill", "coarse_and_fine"]	17.834 ms (5%)		27.58 MiB (1%)	324429
["autofill", "gridpoints_in_polygon", "3201x2401"]	9.131 ms (5%)		1.28 MiB (1%)	7406
["autofill", "gridpoints_in_polygon", "321x241"]	139.082 μs (5%)		63.93 KiB (1%)	923
["autofill", "gridpoints_in_polygon", "33x25"]	15.260 μs (5%)		22.60 KiB (1%)	271

[codecov]

Codecov Report

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