remove physics loader flags in p2 world, fix naming in loader
fixed p2 physics loading format and added the ability to extract a single fixture
PhysicsEditor expoerter updated. Added fixtureKey field. Changed id from lime-json to phaser-json. This ID is used by PhysicEditor to select the appropriate exporter. You have to select Phaser Exporter from the Dropdown list again when you update the exporter. No other breaking changes.
Merge pull request #674 from georgiee/tidy-up-physics

PhysicExporter update, updated flags in Cache & Loader