cpp: tiff: IFD visitors use TileInfo and tile lists
cpp: tiff: IFD readImage reads and transfers pixel data to pixel buffer

Validate the buffer contents by reading the source PNG image and
comparing the two buffers.  Once we have a proper PNG reader, this
simple reading logic can be replaced.
cpp: test: Remove unnecessary use of typename
Merge pull request #1358 from rleigh-dundee/cpp-tiff-pixeldata3

C++: Add TIFF strip and tile reading