Investigate slow procedures in current NetLogo model

[lyashevska]

According to @Dengxiao-Lang potential procedures that may lower the speed of this model: HarvestMemory and AvailableWaterSupply These two procedures were used to calculate the harvest memory and available water memory in the past years (20 years of memory are calculated in the current model), but there is many repeat work in these procedures:

• In the current model, it runs for 100 years, and the memory is calculated in every year.
• Because of system expansion, new farmers will also calculate the memory, whenever there is an expansion there is another 100 years calculation (expansions are: F11-13, F14, F15, F16, F17-19, F20, F21, F22). There are 9 times of 100 years calculation per memory procedure. I thought if we can write these two procedures into a loop, use a uniform equation to calculate the memory, or combine 9 times of 100 years calculation will let the model work faster.

[fdiblen]

Ref: #10 #24