Land Mgmt: fix cant-plant-perennials-twice bug

[#69727506]
Land Mgmt: fix jittering of eroder particles.

[#69726412]

The local variable 'direction' was not being copied back to the patch's property 'direction'. There was no good reason to maintain a separate 'direction' local, so I removed it.
Land Mgmt: make grass "lives forever"

[#69730884]
Land Mgmt: Nate's changes to Netlogo version