Add various missing resources to Xcode project

* oolite-particle-cloud.png and oolite-particle-cloud2.png
* oolite-priorityai.js
* Various JS AI scripts
Embed debug plug-in in application instead of Debug.oxp
Removed Basic-debug.oxp makefile

Since Debug.oxp no longer contains code, a hand-maintained OXP seems
a simpler approach.