Changes

As of this writing, you'd need have to disable several features of 3.1.6 to allow for a successful WASM build.

* For example in <pre>CMakeLists.txt</pre>, the options to build examples, simulate library, and tests for MuJoCo have been turned off by default (changed from ON to OFF). New configurations and target properties for building MuJoCo with Emscripten have been added. This includes defining source files, checking their existence, and setting specific properties and options for building WebAssembly (.wasm) and HTML output. Some target link options have been adjusted, including removing the lodepng library from the target link list.* * In src/user/user_objects.cc comment out the line that includes lodepng.h. Replace the bodies of the mjCHField::LoadPNG and mjCTexture::LoadPNG functions with a single return statement.* * In src/engine/engine_util_errmem.c update the preprocessor condition in the mju_writeLog function by replacing __STDC_VERSION_TIME_H__ with __EMSCRIPTEN__ in the #if directive. The line should now include __EMSCRIPTEN__ in the condition.** In src/engine/engine_crossplatform.h add a conditional block specifically for Emscripten within the preprocessor directive in the engine_crossplatform.h file. Inside this block, include the sort_r.h header and define the mjQUICKSORT and quicksortfunc macros appropriately. This will separate the handling for Apple, Emscripten, and other platforms.** In the cmake/MujocoOptions.cmake file, remove the -Wno-int-in-bool-context compiler warning flag from the list of warnings.** In the CMakeLists.txt file, make the following changes:

Change In `src/user/user_objects.cc`, comment out the default values line that includes `lodepng.h`. Replace the bodies of the options to disable the building of examples, simulate library, tests, `mjCHField::LoadPNG` and Python utility libraries by setting them to OFF`mjCTexture::LoadPNG` functions with a single return statement.

In `src/engine/engine_util_errmem.c`, update the preprocessor condition in the `mju_writeLog` function by replacing `__STDC_VERSION_TIME_H__` with `__EMSCRIPTEN__` in the `#if` directive. The line should now include `__EMSCRIPTEN__` in the condition. In `src/engine/engine_crossplatform.h`, add a conditional block specifically for Emscripten within the preprocessor directive. Inside this block, include the `sort_r.h` header and define the `mjQUICKSORT` and `quicksortfunc` macros appropriately. This will separate the handling for Apple, Emscripten, and other platforms. In the `cmake/MujocoOptions.cmake` file, remove the `-Wno-int-in-bool-context` compiler warning flag from the list of warnings. In the `CMakeLists.txt` file, make the following changes:* Change the default values of the options to disable the building of examples, simulate library, tests, and Python utility libraries by setting them to OFF: * Set `MUJOCO_BUILD_EXAMPLES ` to OFF. * Set `MUJOCO_BUILD_SIMULATE ` to OFF. * Set `MUJOCO_BUILD_TESTS ` to OFF. * Set `MUJOCO_TEST_PYTHON_UTIL ` to OFF.* Remove the `lodepng ` library from the `target_link_libraries ` list for the `mujoco ` target. Also, for example, in `mjxmacro.h`, add explicit casting to `size_t` for the calculations of `key_mpos` and `key_mquat` array sizes, ensuring correct memory allocation and preventing potential integer overflow issues.