API/Demo - gravity influence

[PhoenixIllusion]

Expose per-body gravity influence

Demo:

• press button to switch gravity from Y axis to X axis

Demo:

• vehicle:
  • when in sensor volume, shift gravity on vehicle
  • oriented camera "up" counter to gravity
  • drive from ground on to wall and back
• character virtual : wall walk
  • mirror same logic as above.
  • does not use api, since character virtual does not use system gravity by default
• character virtual : planet/galaxy
  • adopt above logic but extend to mini worlds with jump/ launch between them
  • disable mid-air movement when in launch between planets

[PhoenixIllusion]

Feature Implemented in 1.3.0

• Gravity Influence
• SetGravityOverride
  • GravityInterface - GravityVector, GravityPoint,

Demos Implemented in spirit by:

• [ Character Virtual: Sphere World / Ribbon World ] - lacks multiple world example
• [ Vehicle Kart: Sphere World / Ribbon World ]