Module based spatial distortions

[jonwright]

To be added to blobcorrector.py:

• import pyFAI to get module geometry definitions
• create LUT from small file of offsets + rotations
• read pyFAI nexusdetector files

[jonwright]

Could be done as a table in a columnfile:

# ModuleID slow_start slow_end fast_start fast_end slow_shift fast_shift rotation_angle

This will need a definition of the centre of rotation and whether the shift comes before or after the rotation...