Update: new level, new sawblade mechanics

What's new:

• We've added a second level! There's no level select screen at this point, but you can go to the next level at anytime by pressing Shift+L. More levels are coming soon!
• After a target (diamond) has been picked up a new one will only activate after 6 seconds, but two nova particle effects will signify its location 4 and 2 seconds before it activates.
• Sawblades deteriorate visually after getting hit by players or NPC enemies. After 2 hits, sawblades become dull and will only knock back and not kill colliding players.
• When destroyed, sawblades break into shards just like players.
• New hi-res blob graphics by Tibor.
• Improved head stomp detection outside safe zone; jumping on each others' head in the safe zone results in a bounce but no kills.
• Bugfix: wall jumps didn't have jump sounds.