Analog modeled walking sound is a regression

[lagomorph]

Recent changes to model the walk sound produce a less accurate result than the samples used in the previous releases. The samples were taken from a real board so they sound fine individually. The drawback of them is they can't produce the variation that the real board does as it uses analog feedback to keep them subtly changing. It's great that an attempt is being made to generate the sounds more accurately but until they actually sound closer to the real thing than the samples I don't think this change should be in the release.