ghc::filesystem v1.3.4

• Pull request #69, use wchar_t versions of std::fstream from ghc::filesystem::fstream wrappers on Windows if using GCC with libc++.
• Bugfix for #68, better handling of permission issues for directory iterators when using fs::directory_options::skip_permission_denied and initial support for compilation with emscripten.
• Refactoring for #66, unneeded shared_ptr guards where removed and the file handles closed where needed to avoid unnecessary allocations.
• Bugfix for #63, fixed issues on Windows with clang++ and C++17.
• Pull request #62, various fixes for better Android support, thanks for the PR
• Pull request #61, ghc::filesystem now supports use in projects with disabled exceptions. API signatures using exceptions for error handling are not available in this mode, thanks for the PR (this resolves #60 and #43)