Improved behaviour of mouse-spring interactions.

Also:

- Renamed recently introduced `mjvPerturb` member `reflocalpos` -> `refselpos` and corrected docstring.
- Added `mjvPerturb.localmass`: body spatial inertia at selection point.
- Removed `const` qualifier to `mjData` argument of `mjv_initPerturb()`, to facilitate spatial inertia computation.
- Improved `mj_Object{Velocity, Acceleration}` docstrings, clarifying that rotational velocities precede linear velocities.
- Removed redundant const qualifiers from non pointer arguments to `mju_dot` and `mju_writeNumBytes`.

PiperOrigin-RevId: 511002168
Change-Id: I27400f497947f330072d4abb7c9bf7e71e6c5d49

introspect/functions.py

@@ -2432,7 +2432,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
                  type=ValueType(name='int'),
              ),
          ),
-         doc='Compute object 6D velocity in object-centered frame, world/local orientation.',  # pylint: disable=line-too-long
+         doc='Compute object 6D velocity (rot:lin) in object-centered frame, world/local orientation.',  # pylint: disable=line-too-long
      )),
     ('mj_objectAcceleration',
      FunctionDecl(
@@ -2471,7 +2471,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
                  type=ValueType(name='int'),
              ),
          ),
-         doc='Compute object 6D acceleration in object-centered frame, world/local orientation.',  # pylint: disable=line-too-long
+         doc='Compute object 6D acceleration (rot:lin) in object-centered frame, world/local orientation.',  # pylint: disable=line-too-long
      )),
     ('mj_contactForce',
      FunctionDecl(
@@ -3353,7 +3353,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
              FunctionParameterDecl(
                  name='d',
                  type=PointerType(
-                     inner_type=ValueType(name='mjData', is_const=True),
+                     inner_type=ValueType(name='mjData'),
                  ),
              ),
              FunctionParameterDecl(
@@ -5651,7 +5651,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
              ),
              FunctionParameterDecl(
                  name='n',
-                 type=ValueType(name='int', is_const=True),
+                 type=ValueType(name='int'),
              ),
          ),
          doc='Return dot-product of vec1 and vec2.',
@@ -6978,7 +6978,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          parameters=(
              FunctionParameterDecl(
                  name='nbytes',
-                 type=ValueType(name='size_t', is_const=True),
+                 type=ValueType(name='size_t'),
              ),
          ),
          doc='Return human readable number of bytes using standard letter suffix.',  # pylint: disable=line-too-long