CMake

Return std::shared_ptr for Cell #124

Job	Run time
build (ubuntu-latest, Debug, static, 5.12, x86_64)	37s
build (ubuntu-latest, Debug, static, 6.6.0, x86_64;arm64)	1m 3s
build (ubuntu-latest, Debug, shared, 5.12, x86_64)	39s
build (ubuntu-latest, Debug, shared, 6.6.0, x86_64;arm64)	58s
build (ubuntu-latest, Release, static, 5.12, x86_64)	1m 18s
build (ubuntu-latest, Release, static, 6.6.0, x86_64;arm64)	57s
build (ubuntu-latest, Release, shared, 5.12, x86_64)	50s
build (ubuntu-latest, Release, shared, 6.6.0, x86_64;arm64)	1m 7s
build (windows-latest, Debug, static, 5.12, x86_64)	1m 30s
build (windows-latest, Debug, static, 6.6.0, x86_64;arm64)	1m 13s
build (windows-latest, Debug, shared, 5.12, x86_64)	1m 41s
build (windows-latest, Debug, shared, 6.6.0, x86_64;arm64)	2m 4s
build (windows-latest, Release, static, 5.12, x86_64)	56s
build (windows-latest, Release, static, 6.6.0, x86_64;arm64)	1m 21s
build (windows-latest, Release, shared, 5.12, x86_64)	1m 23s
build (windows-latest, Release, shared, 6.6.0, x86_64;arm64)	2m 1s
build (macos-latest, Debug, static, 5.12, x86_64)	29s
build (macos-latest, Debug, static, 6.6.0, x86_64;arm64)	1m 7s
build (macos-latest, Debug, shared, 5.12, x86_64)	29s
build (macos-latest, Debug, shared, 6.6.0, x86_64;arm64)	1m 10s
build (macos-latest, Release, static, 5.12, x86_64)	33s
build (macos-latest, Release, static, 6.6.0, x86_64;arm64)	1m 11s
build (macos-latest, Release, shared, 5.12, x86_64)	35s
build (macos-latest, Release, shared, 6.6.0, x86_64;arm64)	1m 26s
	26m 38s

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