Should be able to add shapefile as background area

[danlwarren]

[danlwarren]

The more I think about this, the less I'm sure it's worth doing. Since we're not requiring an env argument for check.species, the avenue of using the env to convert shape to raster on the fly as species are created isn't really open.

The other alternative is to build it into the modeling functions (enmtools.maxent, etc), but that's not really satisfactory either as it would require redoing it every time a new model is built.

The other alternative is to write new stuff in all of the modeling and test functions that draws backgrounds etc. from shapes instead of rasters. That's an awful lot of work to just save the user the hassle of clipping an env raster with their shapefile before they create a species range. Not saying it's not worth doing, but I'm not going to consider it a high priority.