add a nifti wrapper for vips7

so nip2 can now load nifti images

add a compat stub for vips_region_shrink()

to keep ABI compat with 8.6

make vips_object_get_args() return an int

since malloc can fail

make test-suite survive make dist

fix a buffer overflow in the tiff reader

see https://github.com/jcupitt/libvips/issues/1039

improve accuracy of vector path

fix make dist

icc_import attaches the input profile if used

icc_import can take a fallback input profile in case the embedded one is
broken or missing. If we use the fallback profile, this change attaches
it to the output image.

This means that icc_import will always output an image with the icc
profile that was used to import it. This helps to make the behaviour of
`thumbnail` more consistent.

See https://github.com/jcupitt/libvips/issues/152

improve changelog

oops fix copy-paste error