HXE's install procedure does not care if files are incomplete

[BinToss]

We should hash files before they are moved to their final destination.
Oftentimes, this issue is due to the storage drive not having enough free space for extraction to %temp%.

We really should be extracting to a temporary directory under the target directory.
Maybe use the "./cache" idea I haven't talked about until now?

[BinToss]

Side note: hashing is serial i.e. to hash a file, you must process the entire file. For large files, this can take quite a while.
It may be better to hash chunks in parallel and store the hashes of the chunks for validation after unpacking.