Remove non unit conversion functions

[ChrisBarker-NOAA]

There's some cruft from things that WebGNOME needed, and had to be put somewhere, but this is not the right place.

What I noticed:

_BurnDuration
waterDensity
rayleighDist

So: are these being used? If so, then they should probably be moved from jsNUCOS to the GNOME code, or maybe a gnome_utilities package, if there's a reason to keep it separate from the GNOME code.

Don't remove any of them from jsNUCOS unless:

1. It's not being used anymore in WebGNOME

2. It's been moved to elsewhere in the WebGNOME codebase.

NOTE: I just found those -- there may be others -- a quick audit is worthwhile.

[ChrisBarker-NOAA]

@coconnor8: I think you found at least one of these, and what it's used for -- could you please put a comment in here about that?

[JamesMakela-NOAA]

• _BurnDuration: is used by webgnomeclient: ./js/views/form/response/insituBurn.js

• waterDensity: is used by webgnomeclient: ./js/model/environment/water.js

• rayleighDist: is used by webgnomeclient: ./js/model/environment/wind.js & ./js/views/form/mover/wind.js

So we could find a different home for these things, but we probably shouldn't just get rid of them.