uses local cache for assets now so should be able to produce an offline build with vcpkg. Only a couple of libraries left that are too big, and the vcpkg repo itself has files that are blocked from the repo. We could get around both issues by utilizing a submodule
update bitmapPng reading from libpng to have context in warnings and errors, also add a bit of a better structure around the read and write functions.
Interlaced PNG's were never being accounted for before so add the png_set_interlace_handling for interlaced pngs
it's getting there, but there have been a few spots noted where it eroneously corrupts text, so we'll have to pull this back out for a bit barring a proper resolution
