Merge pull request #1 from zaojiahua/master

Add drop blood label
support circle sector detect

1 support circle sector detect
2 support face to enemy
Merge pull request #2 from calfjohn/master

support circle sector detect
Merge pull request #3 from zaojiahua/master

BillboardParticleSystem binding
add TestAIScene.
merge with fusijie/master
ignore main.lua while push