Improve Unicode support #1567

Job	Run time
cppcheck	11m 20s
code formatting check	29s
min features with gcc	3m 6s
min features with g++	3m 1s
min features with clang	3m 16s
max features with gcc	4m 5s
max features with g++	3m 32s
max features with clang	4m 57s
max features with gcc and DEBUG	2m 37s
max features with gcc for 32-bit arch (legacy OS)	2m 46s
max features with g++ for 32-bit arch (legacy OS)	2m 3s
max features with clang for 32-bit arch (legacy OS)	3m 0s
	44m 12s

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