r700 - Scripting Changes

Just an update again till I get some verifications its looking good. I'm now starting work on a new map editing mode which should be closer to how MCEdit works in functionality than playing normal minecraft.

• Effect scripting is added (effect)
• ScriptEntity spawnParticle(String particleType, double x, double y, double z, double arg1, double arg2, double arg3)
• boolean replaceTexture(String textureToReplace, String replacement)
• revertTextures()
• setOverlay(String overlay)
• clearOverlay()
• setFogColor(float r, float g, float b)
• revertFogColor()
• setFogDensity(float start, float end)
• revertFogDensity()
• Script Block OnUpdate only occurs now if the block is triggered
• Adds global scripts
• OnNewSave - First time a save is created this runs
• OnLoad - Every time a save is created or loaded this runs next
• OnUpdate - Runs at the start of every tick
• AdventureCraft shouldn't crash now if missing version.txt
• Adds a new config screen via /config to configure global scripts
• getItemInSlot and decrementItem will return undefined back if there is no item