Log Message:
Import tkpng-0.9 as wip/tkpng.

TkPNG is an open source binary package that adds PNG photo image support to
Tcl/Tk. Although other extensions such as Img  also add support for PNG images,
this package was designed to be lightweight, not depending on libpng nor
implementing other image formats, and suitable for inclusion in the Tk core. Tk
does not currently have native support for any image formats that allow for
alpha (partial-transparency) channels, although it does have support for alpha
blending internally. Using alpha channels for smooth blending and anti-aliasing
is a great way to improve the appearance of GUI applications built with Tcl/Tk,
especially when combined with Tile.