scripts/exe/gen_ide.py writes build/Ragexe.sln (Makefile project: Build runs
scripts/exe/build_exe.py like td compile, Rebuild/Clean, Debug starts
build/exe/Ragexe.exe; all units and headers with per-unit IntelliSense flags)
and build/editor-x86/compile_commands.json (clangd, VS Code, CLion).
The hand-written CMakeLists.txt covered 392 of 980 units without the
per-unit flags and was unused by clank; removed with its ThirdParty file.
.clangd drops /execution-charset (CP949), which clang does not accept.
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