Various changes:

* Use enum class instead of enum (except for the enums for the resource IDs, not really necessary there).
* For NCSF specifically, included a function to convert an enum class to its underlying integral type (as this is needed for use with the std::bitset class).
* Cleanup headers so all the ones needed in a file are explicitly included even if they may possibly be included in another header.
* Used forward declarations in a few spots.
* Explicitly namespaced all (u)int*_t uses (this might seem like overkill, but it helps me see when the standard types are being used with a simple search for std::).
* Made sure it all builds with MinGW-w64 as well (both gcc and clang).
* Removed some std::move from DialogBuilder.cpp based on clang's warnings for that.
* Replaced use of std::copy_n on strings in DialogBuilder.cpp with my CopyToString functions that use wcscpy.
* Replaced CHAR_MIN/CHAR_MAX in eqstr.h and ltstr.h with std::numeric_limits<char>::min/max().