Added support for Steam achievements.
Currently, there are 18 achievements available:
- Iron Jaws
- Wet Foot, Dead Foot
- Chain Reaction
- Tuned In
- Can of Trouble
- Blind Enemy
- Hammer Time
- No Time to Waste
- Survivor
- Masochist
- Time Slayer
- Lights Out
- Clumsy Grip
- Distraction Tactics
- House Wrecker
- Curator of Horror
- Connected Threads
- The Final Chop