happy 30th, PNG!

It's not often one of the big anniversaries comes around, so, you 
know...

The spec was finalized 30 years ago today, and conformant 
implementations started showing up shortly thereafter. (Well, there were 
already some even beforehand since they were necessary to test the spec 
itself. Tip of the hat to Glenn Randers-Pehrson, more commonly known for 
shepherding libpng until his death a few years ago, but who also rapidly 
iterated on at least one or two experimental PNG apps prior to the 
spec's completion and created some of the earliest still-valid PNG 
images.)

Greg