Measure, test 3 different styles of run.

The measure method of a RawRun instance now works for new style images.

Tidied up the config file and made perspective / barrel correction
coeffs more explicit.

Fixed an error in the physical location of the new style markers (lower
left was incorrectly placed).

The reference images have changed. Images are now cropped to the same
values in *physical* space, rather than pixel space - means that images
can in principle be overlaid, aligning with each other.

Bottom edge of images is now flush with the tank bottom.

Updated tests to reflect changes.

Various tidying.