add z-order & add gitignore
Merge pull request #17 from Ryeeeeee/master

add z-order & add gitignore
bullet missiles slower, corrected enemy spawn
updated 3d models
Merge branch 'master' of https://github.com/Wu-Hao/Moon3D

Conflicts:
	proj.ios_mac/Moon3d.xcodeproj/project.pbxproj