Prediction of typhoon movement

[vicksonzero]

Adding typhoon prediction path should be fun, since it:

• adds realism by making it look like weather charts
• improves gameplay by telling player where to defend
• makes it easier to debug

I suggest changing the AI of the typhoon to follow a pre-defined path, and the path is computed before the typhoon spawns

[vicksonzero]

try to let players deduce some kind of pattern of waves of attacks, so that they can plan a tactic for it