References to `DETECTOR_OUT_3D` remain in the McCode repository

[g5t]

According to a comment in #200 the DETECTOR_OUT_3D macro was removed sometime between McStas 2.0 and 2.1, yet it is still referenced https://github.com/search?q=repo%3AMcStasMcXtrace%2FMcCode%20detector_out_3d&type=code in multiple places including syntax highlighting for (some) editors.

Since the macro was removed from the language, can the highlighting also be removed to prevent misleading component developers contemplating, e.g., producing 3-D monitor output?