Hell freezes

• NEW: MSVC support, from @CaseyCarter 🎉 (See the docs for the list of supported compilers.)
• NEW: view::enumerate, from @MikeGitb
• NEW: view::addressof, from @tower120
• NEW: unstable_remove_if algorithm and action, from @tower120
• NEW: adjacent_remove_if algorithm and action, from @tower120
• NEW: ostream_joiner, from @sv1990
• view::drop_while and view::take_while get projection support, from @mrpi
• view::filter and view::remove_if get projection support, from @mrpi
• view::unique accepts optional comparison operator, from @tete17
• action::slice supports sliding from the end, from @tete17
• Support coroutines on MSVC, from @CaseyCarter
• Faster view::generate_n, from GitHub user @tower120
• Improved aligned new detection for libc++ on iOS, from @mtak-
• Various CMake improvements, from @JohelEGP
• view_adaptor supports basic_iterator-style mixins, from @tower120
• Fix ranges::advance for random-access iterators for n==0, from @tower120
• Bugs fixed: #755, #759, #942, #946, #952, #975, #978, #986, #996, #1041, #1047, #1088, #1094, #1107, #1129