- proper gzip download for disk system (aka WNI reinventing the Content-Encoding: gzip wheel)
- send Last-Modified for static files
- send wtv-checksum for all disk system downloads
- other fixes
- move wtv-update to wtv-disk
- allow accessing wtv-disk:/sync?group=&diskmap=
- rewrite Download List generation to be more proper
- only send files if diskmap has changed
- allow force redownload with &force=true
