Windows Installer: AtomicParsley download location changed due to download failure

[dinkypumpkin]

BitBucket borked the AtomicParsley download used by the Windows 
installer.  It looks like they've blocked it unless you download from 
their site, but I'm not sure what is going on.  It could just be some 
temporary problem.  They've broken the download before, so I've 
relocated AtomicParsley and it appears to be working again.