windows binaries don't work on old windows

[simonmichael]

rwp reported both windows binaries linked on the download page failing on Windows XP (in different ways). These binaries are built with 64-bit stack on Appveyor's 64-bit windows environment. We need someone with access to windows versions older than windows 7 to investigate and clarify the windows version requirement for these binaries run on, so we can document that. Also if possible suggest how to produce binaries that will work on older windows, to support our "just works" goal.