Minor features and a makeshift html5 version

HTML5 version only works with Chrome because Itch.io only support SharedArrayBuffer on Chrome. I don't know enough about the subject to tell if this is a itch.io problem or other browsers' problem.

• Added strafe function, reduced speed but lock aim direction.
• Minor spawn protection, random spawn enemies longer spawn near player. Fixed spawned will still spawn where they were suppose to
• Increase invincibility duration after taking damage.
• Cheat: press F1 after "Mission Start" to get max unlocked firepower. It won't give you power ups you haven't unlocked by leveling Org.