fix vipsthumbnail crop with very non-square images

thanks Alessandro
changelog update too
drop the default max operations

the cache defaulted to 10,000 operations, fine for nip2, not fine for
batch-style applications

thanks Rafael
crash-causing typo in vips_rawsave()

thanks Alessandro
ooops, sorry Andrea
Merge remote-tracking branch 'origin/7.38'
Merge remote-tracking branch 'origin/master' into hough

Conflicts:
	ChangeLog