Improve spatial distribution of --retain-points-multiplier features

2.65.0

• Improve spatial distribution of --retain-points-multiplier features
• Add --preserve-multiplier-density-threshold option to maintain minimum density of multiplier features

test-ecf01f22

Only let --preserve-point-density-threshold shift density around

test-b1466547

Revert "Revert "The multiplier cap was a bad idea""

This reverts commit 80f7cb1c0e8247caba5ec1b0f9e9974bf9145d43.

test-1eb49860

Oh, I didn't git add the code changes

test-b9b55db5

Remove the multiplier sequence, which should no longer matter

test-a26e4130

Limit feature expansion from multiplier density to 2x

test-6f8273a4

The multiplier cap was a bad idea

test-71cf446a

Fix more tests

test-01f14a42

Add a flag to retain multiplier features by minimum distance

test-467a7c59

Choose the megatile features from those that will be in the next N zooms