Use consistent color scheme for wind vectors in KMZ output

[nwagenbrenner]

Many users have requested this. To do this we'll have to defer file writing until the end of the simulation and scale the vectors according to all timesteps. We should probably have the option to do it either way, defer to the end with a consistent legend or write after each time step, maybe with a config option. Deferring to the end should be the default.