Feat/context #77

Job	Run time
android (-O0)	2m 48s
gcc-linux (-O0)	3m 23s
android (-Ofast -flto -DNDEBUG)	2m 18s
clang-macosx (-O0)	1m 53s
gcc-linux (-Ofast -flto=auto -DNDEBUG)	3m 36s
clang-linux (-O0)	3m 32s
clang-macosx (-O0 -stdlib=libc++, -stdlib=libc++)	3m 9s
clang-macosx (-Ofast -flto -DNDEBUG)	3m 44s
clang-linux (-Ofast -flto -DNDEBUG)	4m 4s
gcc-macosx (-O0)	3m 37s
clang-macosx (-Ofast -flto -DNDEBUG -stdlib=libc++, -stdlib=libc++)	4m 0s
gcc-macosx (-Ofast -flto -DNDEBUG)	5m 4s
clang-linux (-Ofast -flto -DNDEBUG -stdlib=libc++, -stdlib=libc++)	4m 5s
clang-linux (-O0 -stdlib=libc++, -stdlib=libc++)	3m 38s
	48m 51s

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