go.image/tiff: decoder support tiled tiff format

Use these commands to generate testdata:
tiffcp -s -r 64 video-001.tiff video-001-strip-64.tiff
tiffcp -t -l 64 -w 64 video-001.tiff video-001-tile-64x64.tiff

R=golang-dev, nigeltao, bsiegert
CC=golang-dev
https://golang.org/cl/13453043
5 files changed