error message if only one bound is inf

[tylerflex]

No description provided.

[xin-flex]

Simplified it as:

Bounds of (-inf, 4) supplied along one dimension. We currently don't support a single inf value in bounds for Box. To construct a semi-infinite Box, please supply a large number instead of inf so that this bound extends outside of the Simulation domain including PML.

[tylerflex]

Thanks, I actually edited this just a bit. Because the from_bounds is not necessarily used for within Simulation, I just made the error message a bit more general. Feel free to suggest a different edit and I'll change it

"Bounds of (pt_min, pt_max) supplied along one dimension. 
We currently don't support a single ``inf`` value in bounds for ``Box``. 
To construct a semi-infinite ``Box``, please supply a large enough number instead of ``inf``. 
For example, a location extending outside of the Simulation domain (including PML)."