Fixes Pyramids

Pyramids were broken when they were solid, the platform code started
each layer at 0, 0 causing the pyramid to be stacked into the corner
rather than each layer centered. I changed the platform code so that it
can have different starting coords while defaulting to old behavior. I
have also tweaked the code so that when it is generating "backwards"
iterates downwards rather than iterating upwards while subtracting from
the max, this is less lines and more accurate.