Remove copy_back from Python bindings and mj_copyBack from the C API.

PiperOrigin-RevId: 687377331
Change-Id: I355493d92857418b08b5aa90ea38cebe5c475314

doc/APIreference/functions.rst

@@ -87,15 +87,6 @@ mj_freeLastXML
 
 Free last XML model if loaded. Called internally at each load.
 
-.. _mj_copyBack:
-
-mj_copyBack
-~~~~~~~~~~~
-
-.. mujoco-include:: mj_copyBack
-
-Copy (possibly modified) model fields back into spec.
-
 .. _mj_saveXMLString:
 
 mj_saveXMLString

doc/includes/references.h

@@ -3133,7 +3133,6 @@ mjModel* mj_compile(mjSpec* s, const mjVFS* vfs);
 int mj_recompile(mjSpec* s, const mjVFS* vfs, mjModel* m, mjData* d);
 int mj_saveLastXML(const char* filename, const mjModel* m, char* error, int error_sz);
 void mj_freeLastXML(void);
-void mj_copyBack(mjSpec* s, const mjModel* m);
 int mj_saveXMLString(const mjSpec* s, char* xml, int xml_sz, char* error, int error_sz);
 int mj_saveXML(const mjSpec* s, const char* filename, char* error, int error_sz);
 void mj_step(const mjModel* m, mjData* d);