Add support for building as shared library and refactor header-only build config #380

Job	Run time
Ubuntu GCC Release	2m 22s
Ubuntu GCC Debug	1m 13s
Ubuntu GCC noexcept Release	1m 10s
Ubuntu GCC noexcept Debug	57s
Ubuntu GCC notime Release	1m 39s
Ubuntu GCC notime Debug	1m 0s
Ubuntu GCC nounity Release	1m 54s
Ubuntu GCC nounity Debug	57s
Ubuntu GCC header-only Release	1m 29s
Ubuntu GCC header-only Debug	52s
Ubuntu GCC shared Release	1m 36s
Ubuntu GCC shared Debug	1m 11s
Ubuntu Clang Release	2m 3s
Ubuntu Clang Debug	1m 38s
Ubuntu Clang noexcept Release	1m 9s
Ubuntu Clang noexcept Debug	52s
Windows 32 Release	4m 14s
Windows 32 Debug	1m 48s
Windows 64 Release	5m 10s
Windows 64 Debug	2m 8s
Windows 64 noexcept Release	5m 33s
Windows 64 noexcept Debug	2m 25s
Windows 64 shared Release	4m 8s
Windows 64 shared Debug	2m 7s
MacOS Release	2m 2s
MacOS Debug	1m 22s
MacOS noexcept Release	1m 46s
MacOS noexcept Debug	1m 12s
WebAssembly Release	4m 20s
WebAssembly Debug	1m 44s
WebAssembly noexcept Release	2m 0s
WebAssembly noexcept Debug	1m 15s
	1h 5m 16s

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