Get translated surface coefficient

[tjlaboss]

Is your feature request related to a problem? Please describe.
Transformed surfaces can be deceptive. It is sometimes useful to know the true location of a surface in a model.

Consider the following example:

Transformed Surface Example
c Cells
1 0  -10  +11  -12  imp:n=1  $ inside cylinder
2 0  +10: -11: +12  imp:n=0  $ graveyard

c Surfaces
10   cz  1.0
11 1 pz 0.0  $ bottom surface 
12 3 pz 1.0  $ top surface

c Data Cards
tr1  0.0  0.0  -1.0  $ shift z down 1.0 cm
tr3  0.0  0.0  +3.0  $ shift z  up  3.0 cm

If one wanted to know the height of Cell 1, he would have to check for transforms and apply any relevant transform manually.

Describe the solution you'd like
Add a property that applies the (x, y, z) translation from a transform to the relevant surface coefficients.

>>> # False height
>>> model.surfaces[12].surface_constants[0] - model.surfaces[11].surface_constants[0] 
1.0
>>> # True height
>>> model.surfaces[12].translated_constants[0] - model.surfaces[11].translated_constants[0] 
5.0

Describe alternatives you've considered

• Obviously, you could also apply the rotation, but that gets messy very quickly; translation is relatively simple.
• You could get a shifted surface: problem.surfaces.shift_x, y, z #74

Additional context
Also related to: #73