Web raster symbology test fix, part of issues #999 and #1001

[ChloeSeeborg]

Changed interpolation method from exact to discrete for temperature and vapor pressure symbology (Issue #999). Added extra row to hand symbology to try and correct values > 0 from being displayed in the 0 class (Issue #1001).

[MattReimer]

Looks fine and a perfectly ok thing to test a non-working symbology.

@ChloeSeeborg did it work?

[ChloeSeeborg]

@MattReimer It looks like the fix mostly worked. Mean and Maximum temperature layers look good. Minimum and Dew Point layers are still not displaying at all. They use the same symbology as mean and max so that's confusing.

The vapor pressure layers look good.

The attempt to fix the hand symbology did not work, it looks like the change had no effect on how it's being displayed.

[MattReimer]

@ChloeSeeborg One thing I should probably bring up is that those tiles are cached pretty heavily (your browser caches them but so does the server). I'm not saying that's what happening here but it could be muddying the waters a bit so there's a chance you could be seeing old tiles. A good test would be trying it on a project you haven't opened before.

If those layers are still a problem after we've ruled out caching then the next step is to download the projects with the actual rasters and see if there is some reason the values aren't working the way we expect.

[ChloeSeeborg]

@MattReimer I looked at a new HUC and the min and dew point temperature layers look good, so caching was the issue there. The hand layer is still displaying cells as the incorrect class.