First steps in tidying image/kernel_read_write tests (#1121)

* Move common global variable and functions to header

InitFloatCoords for 3D read images has also been renamed
so it can later be used as a common function

Contributes #616

Signed-off-by: Ellen Norris-Thompson <[email protected]>

* Set-up for using 3D functions as a base

test_read_image_3D had been moved to common.cpp (and renamed
test_read_image) along with corresponding
determine_validation_error_offset and InitFloatCoords.

Only function names and the formatting have been changed.

Contributes #616

Signed-off-by: Ellen Norris-Thompson <[email protected]>
7 files changed