Switch to MSDelta for binary diff/patch

This PR forgets all about bsdiff/bspatch, and switches us to DeltaCompressionDotNet, which uses mspatchc.dll, the delta compression API that Windows uses.

### Here Be Dragons

This patch system is obviously **incompatible** with the previous one! To migrate, you'll have to:

1. Ship your next update that has this change, in as a *Full Update*.
1. Make sure in that full update, to ship Squirrel.exe in the update itself (to update the updater).

## TODO:

- [ ] Fix broken tests that rely on fixtures generated by the old system