Implement time-varying field

Well, just reading the field anyway.

The log packing thing didn't seem to work, but
the accuracy is fine for our purposes it seems.

What's not fine is that the floating point accuracy for
texture lookups makes the edges of continents change depending
on which slice of the texture we're on.

Thus, I'll likely still keep the PNG packing code, but unpack
it to 8 individual textures.

Also, might try floating point textures for communication between
layers, so the noise advection/LIC can be smoother.
Split timeslices pre-opengl, fix edges

Stupid land, again.

Well, maybe I should load raw floating point textures, since in theory
s3 or wherever I host the timeslice data will compress it in flight (and
JS inflation libraries don't seem to exist in mature form).
Seed initial blend
Implement time animation

Looks really cool. Now to get more data.

I could grab the rest of blue marble to make the land vary too...
Implement changing earth texture

For art's sake!