Hasher alpha v2

Thanks to szentigrad3, I refactored how Hasher downloads miners. It's not parallel anymore and most importantly, it shouldn't be able to lock itself. Much cleaner downloads, unzipping and installations, hopefully a good fix to the issue.

Otherwise, logs are getting richer in C:\Users\<USER>\AppData\Roaming\Hasher\log.log. I'll need to create a new file at each launch to prevent overcrowding the logs, but this can wait a bit.