Adds the ability to craft items to SteamBot

From the swamp of controversy stemming from Issue #57, I give to you **Crafting**.

* Added `LaunchTF2()` function
* Added `QuitTF2()` function
* Added `CraftItems(List<ulong> items)` function
* Added a new class which is needed for the `CraftItems` function to work

Enjoy.