Remove arrays from AlgorithmSmoothByInput.

Summary: This removes the array creation in AlgorithmSmoothByInput, addressing T122.  This should reduce the amount of GC hits required when the game is running (although since in-game doesn't use the full generation we can't tell yet).

Test Plan: Make sure the generation still runs properly (test in the world gen viewer to make sure the algorithm is still working).

Reviewers: Sabre070, buildbot

CC: buildbot

Maniphest Tasks: T122

Differential Revision: http://code.redpointsoftware.com.au/D103