Maul2D v1.2.0

Maul2D 1.2.0: the integrator surface

Everything an engine layer or editor needs to walk, read, and
rebuild a world from a bare world id:

• Enumeration: m2World_GetBodies/GetJoints/GetChains,
  m2Body_GetShapes, m2Chain_GetShapes. Ascending slot order,
  truthful totals.
• Introspection: body type, local center, bullet flag, gravity
  scale; shape type, sensor flag, filter, density; joint type and
  endpoint bodies.
• Geometry readback: exact stored bits for all five shape kinds.
• Joint parameter readback: every def field has a getter, including
  break limits.

The surface is provably complete: the mirror test rebuilds a world
from public getters alone and holds hash equality with the original
through 90 steps.

No wire or snapshot changes; every addition is a pure reader, proven
by byte-identical gate hashes across the three slices.