Using landscape to initialise subdivisions so that computational load is more balanced

In a test run of simulating 10 days with 5 flower patch clusters, this increased CPU utilisation from 336% to 364% when using 4 threads. Also the distribution of flower patches changed from

 488480 flower_patch_locations_00.bin
 814832 flower_patch_locations_01.bin
 511280 flower_patch_locations_02.bin
 665960 flower_patch_locations_03.bin

to

 603032 flower_patch_locations_00.bin
 643088 flower_patch_locations_01.bin
 641672 flower_patch_locations_02.bin
 597344 flower_patch_locations_03.bin

showing a much more even distribution.

(The effect should be more pronounced with more threads as the distribution of flower patch can be matched more accurately.)