Implement HalfSpace.mcnp_str() and HalfSpace.format_for_mcnp_input()

[tjlaboss]

Is your feature request related to a problem? Please describe.

I'm always frustrated when...

...working with a cell definition and wanting to print out just the geometry string.

>>> cell = montepy.Cell("1 0 -123 234 imp:n=1 u=2")
>>> cell.mcnp_str()
1 0 -123 234 imp:n=1 u=2
>>> cell.geometry
(l: s: False, is_c: False, div: SURFACE: 123, CZ| op: Operator.INTERSECTION| r:s: True, is_c: False, div: SURFACE: 234, PZ)
>>> cell.geometry.mcnp_str()
AttributeError: 'HalfSpace' object has no attribute 'mcnp_str'

Describe the solution you'd like

Implement HalfSpace.format_for_mcnp_input(). Move the geometry/region formatting to HalfSpace.format_for_mcnp_input(). Call that function from within Cell.format_for_mcnp_input(). Finally, implement HalfSpace.mcnp_str().

>>> cell.geometry.mcnp_str()
-123 234

Describe alternatives you've considered

Doing the same thing with an inheritance scheme for all printable objects.

[MicahGale]

You don't like my str(geom)? :P

In [5]: str(cell.geometry)
Out[5]: '(-123*+234)'

[tjlaboss]

More than repr(geom) and less than geom.mcnp_str().