Release v0.26.0 + update to Rapier 0.19

[sebcrozet]

This is an update to Rapier 0.19 which includes several stability improvements
and character-controller fix. Please have a look at the
0.19 changelog of Rapier.

Modified

• Renamed Toi/ToiDetails to ShapeCastHit/ShapeCastHitDetails.
• Switch to rapier’s built-in length_unit instead of explicitly scaling shapes with physics_scale.
• Linear shape-casting functions now take a ShapeCastOptions parameter that describes how the shape-cast should
  behave on special-cases (like toi == 0).
• Internal edge correction is now opt-in with the TriMeshFlags::FIX_INTERNAL_EDGES and
  HeightFieldFlags::FIX_INTERNAL_EDGES flags.
• Rename RayIntersection::toi to RayIntersection::time_of_impact.

Fix

• Fix character controller occasionally getting stuck against vertical walls.

Added

• Add the SoftCcd (for rigid-bodies) and ContactSkin (for colliders) components. See
  rapier#625 for details on the features they enable.