Unify static linking for all operating systems and improve README #358

Job	Run time
build_dynamic_and_test_macos	1m 52s
build_dynamic_and_test_ubuntu	1m 42s
build_dynamic_and_test_windows_pre	2m 15s
build_static_and_test_ubuntu	6m 43s
build_static_and_test_ubuntu_with_system_ffmpeg	57s
docs_rs_check	1m 16s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static, -Ctarget-feature=+cr...	20m 2s
rust_clippy_check_ubuntu	5m 24s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static-md, static, vcpkg)	19m 4s
rust_clippy_check_windows	19m 25s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows, dynamic, vcpkg)	18m 58s
rustfmt_check (macos-latest)	8s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static, -Ctarget-feature=+crt-...	19m 43s
rustfmt_check (windows-latest)	28s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static-md, static, vcpkg)	18m 57s
rustfmt_check (ubuntu-latest)	4s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows, dynamic, vcpkg)	18m 56s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static-md, static, dir_vars)	19m 12s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static-md, static, pkg_config)	19m 33s
build_dynamic_and_test_windows	2m 44s
	3h 17m 23s

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