RehashingAA.rehashThresholdMultiplier

The modifier by how much more entries must be added before another rehash takes place, with regards to the current aa length.

A multiplier of 2.0 means the associative array will be rehashed as soon as its length doubles in size. Must be more than 1.

struct RehashingAA(AA : V[K], V, K)
double rehashThresholdMultiplier;