This is a usual CMake way of ensuring that IDEs have a way of showing
all source files which comprise this header-only library. It works in
the Qt Creator, for example.

Compatibility with Oracle Developer Studio 12.5 on  Solaris

Fix Klockwork compilation warning

Fix compilation error C2664  on VS2013

1. Removing "return" from void functions.
2. Using "const" for operator= argument.

No converting constructor

Fix several compiler warnings

 vs 2013 not supports std::atomic_int

Exposed logger sinks.

update os.h to fix filesize() on older win32

_fstat() always fails under older 32bit WinXP/Win2003 targets.

_filelength() just works for both WinXP SDK and later Win7+ 32bit targets.