better space handling, and a transparent DEBUG banner to create overlays #395

Job	Run time
build-linux64 (linux64, 64gcc6)	3m 2s
build-emscripten (emscripten)	3m 9s
build-ios-tvos (ios, macos)	1m 45s
build-macos (osx, xcode)	1m 9s
build-ios-tvos (tvos, macos)	4m 35s
build-macos (osx, makefiles)	1m 53s
build-msys2 (mingw64)	4m 21s
build-vs2022 (x64)	3m 23s
build-msys2 (ucrt64)	4m 4s
rpi-build (armv6l, armhf, arm-linux-gnueabihf, 1)	1m 40s
build-vs2022 (ARM64)	2m 45s
build-msys2 (clang64)	4m 22s
rpi-build (aarch64, arm64, aarch64-linux-gnu, 1)	1m 39s
build-vs2022 (ARM64EC)	2m 56s
	40m 43s

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