rtPupalMortalityGrid: tsetse pupal mortality on a GRID
In AndySouth/rtsetse: simulating tsetse fly populations

rtPupalMortalityGrid applies rtPupalMortality to a grid. It does that by simply calling that function for each cell in the grid.

1 2	rtPupalMortalityGrid(aGridPup, pMort = 0.25, propDD = 0.25, mMortMultGridPup = NULL, mCarryCap = NULL, iCarryCap = NULL)

`aGridPup`	array with the age distributions of pupal males & females [y,x,sex,age]
`pMort`	a mortality probability
`propDD`	proportion of mortality that is density dependent
`mMortMultGridPup`	an optional grid of mortality multipliers (derived from vegetation)
`mCarryCap`	a matrix of Carrying Capacities for each cell as an integer (an alternative to iCarryCap)
`iCarryCap`	a single integer Carrying Capacities for all cells as an integer (an alternative to mCarryCap)