Unused imports and other prospect (non)dependencies

I'm trying to narrow down the list of dependencies for prospect to the smallest possible set. As far as I can tell, the dependencies break down like this:

* Packages that are absolutely required because they are explicitly imported.
- `bokeh`
- `numpy`
- `astropy`
* Packages that can be optionally imported, and prospect can still run if they are not imported.
- `desiutil`: but `prospect.scripts.prospect_pages` will fail if `desiutil` is not installed
- `desitarget`
- `desispec`: but `prospect.scripts.prospect_pages` will fail if `desispec` is not installed
- `redrock`
- `specutils`
* Packages that do not appear to be necessary at all.
- `jinja2`: this package is *never* imported. `grep -r -i jinja2 *` shows that no Python packages use it.
- `scipy.ndimage.filters`: this package is imported in two different places, but *never* used.

If I'm wrong about the last two, please let me know where these packages are used.