RF: remove unused inport in funcs
NF: dot_reduce utility function

Function for chaining dot product across arrays, particularly useful for
dot product of affine components
RF: rewrite parrec affine routine after testing

Michael's new data had enough variation to test most combinations of
transformations.  The key seems to be to transform first to the Philips
axes (anterior-posterior, inferior-superior, right-left), then apply the
rotations, before finally taking into RAS output space.

Add the PAR files for Michael's test data set and test against the
current versions of the affines, which I checked by reslicing the data
with the affines (see check_parrec_reslice.py script).