seed_production: Mean Seed Production
In petrelharp/landsim: Simulate Populations on Landscapes

Find the mean seed production, by genotype, given the local numbers of seeding individuals and pollen density, by genotype.

1	seed_production(seeders, pollen, mating, fecundity = 1)

`seeders`	A numeric matrix of numbers of seeding individuals, with number of columns equal to the number of genotypes.
`pollen`	A numeric matrix of pollen density, with number of columns equal to the number of genotypes.
`mating`	An array with probabilities of producing each genotype from each parental genotype.
`fecundity`	Scaling factor that multiplies the resulting matrix.