Refinement during indexing: strained or larger samples

[jonwright]

Unit cell may approximately known (but not exactly), e.g. high pressure or chemically different etc.
Grain position may be relatively far from the centre of rotation.

Still the far-field case that peaks can be assigned hkl indices from their twotheta.

Add a (constrained?) cell parameter refinement or position refinement (or both) during indexing.

[jonwright]

see also #77, shift cell parameters before indexing too ?

[jonwright]

This is effectively taken care of by running grid_index_parallel. But that is not an easy option from the Tk GUI. But the lack of GUI is a different problem, so closing.