fix: Allow `swampCost` and `plainCost` as options in _findPath2 (#62)
fix: Allow `swampCost` and `plainCost` as options in _findPath2 (#62)

* Allow `swampCost` and `plainCost` as options in _findPath2

Right now the only way to change the swamp and plain cost is
`ignoreRoads`, but that doesn’t allow explicit control.

Adding this in `_findPath2` will enable it in a variety of areas,
including `moveTo`.

* *Actually* add terrain costs in

screeps/engine