made starting of minecraft asyncronous (threaded)
stuff

- scrolling in the log
- Only download minecraft jars & liberaries if they exist
- SessionInfo now uses correct username for mojang accounts
- MinecraftVersion updated to work with snapshots n' stuff
Merge pull request #73 from Northcode/dev-Andreas

Dev andreas
Merge pull request #74 from Northcode/dev-Jens

Dev jens
Merge pull request #75 from Northcode/dev

Dev