Manually prepend `lib` and append `.a` to the static library names
provided by the cmake pkg-config cmake module. This is necessary because
the `find_library()` function always prefers the shared object file if
the library name is "unqualified" and unfortunately the cmake pkg-config
module seems to provide only "unqualified" library names through
`*_PKG_STATIC_LIBIRARIES`.
Add MSBuild targets for net46 target framework which copy both x86 and
x64 libsodium binaries into corresponding folders. This allows AnyCPU
applications to load the appropriate binary at runtime via
`LoadLibraryEx`.
Henrik Gaßmann