* Update boost to 1.69. Fixes#5023
- Remove boost-signal (rationale: deprecated and removed in 1.69)
- Remove boost-hana workaround by xiangfan-ms #4186#3579 (rationale: 1.69 incorporates required fixes in hana master branch; builds fine in VS2017 15.9)
* [boost-signals] Restore signals from boost 1.68 because it is required by wt
* [boost-vcpkg-helpers] Improve dependency detection
* [boost-iostreams] Revert to cmake build to enable dependencies
* [boost-iostreams] Fix use of zstd in static builds
* [libtorrent] Update to 1.2.0
* [wt] Update to 4.0.5
* [boost-safe-numerics] [boost-vcpkg-helpers] Added safe_numerics; slight mod to regex match
* [hpx] Backport boost 1.69 fixes
* [libtorrent] Clean up cmake file installation
* [boost-type-traits] Fix MSVC arm
* making sure there is a leading <compileflags> even if CMAKE_CXX_FLAGS do not start with a whitespace
* making sure there is a leading <compileflags> even if CMAKE_CXX_FLAGS do not start with a whitespace
* full support for CXXFLAGS, CFLAGS and LDFLAGS throughout the boost-modular-build-helper
* [boost-modular-build-helper] Bump version and use CMAKE_* macros since the VCPKG_* macros are not passed in
* [boost-type-erasure] Depend on boost-thread even in UWP
