AutoHost_commands.cs: improve !setengine command
1) guess full version name (ie: !setengine 97.0.1-255 --into--> 97.0.1-255-githash)
2) 2 additional error message (ie: "No such engine version" and "Engine downloading. 0 %")
AutoHost_commands.cs: removed folder check as proposed
(and because Benchmarker's engine list work perfectly fine).
AutoHost_commands.cs: found a typo. "Password Remoded" -> "Password Removed"
AutoHost_commands.cs: !setengine use threading, keep engine list indefinitely for repeated use, and keep list for at least 10 minute before re-fetching new list (when no match is found).
Merge pull request #68 from xponen/setengine

AutoHost_commands.cs: improve !setengine command