Snap! (0.9.7)

Changes:

• When multiple non-human players, let AI prefer to target other AIs before human in both defense and attack.
• Give human bonus ships at the start (+10%, +20%, +25%) on (easy, normal, hard). 
• Run AI less frequently (2.0s, 2.0s, 1.5s) on (easy, normal, hard) - easy also uses simple AI.
• Fix options/credits not getting default focus
• Fix level info not updating when going back to main screen after game end