Version 0.16.0

Summary

• Rotating and daily log files keep their extension (e.g "mylog.3.txt" and not "mylog.txt.3")
• Optional support for printf formatting (enabled using #define SPDLOG_FMT_PRINTF) - Thanks @fogo
• Async log: increased sleep to to 500ms the worker in loop when the queue is empty
• Fixed thread safety bug in flush() - added lock on flush in base_sink
• Breaking change: Removed all *_if functions (trace_if, debug_if, info_if,..) because they are redundant and confusing way to preform simple if
• Swallow only std::exceptions. report about, and re-throw other, unexpected exception types.
• Support msvc_sink on all windows compiler (windebug-sink) - Thanks @jpcima
• Added facilty param for syslog - Thanks @adubovikov
• correct include path for sink/syslog_sink.h - Thanks @jpcima
• Fix include paths - Thanks @daylanKifky
• Some fixes in the async queue size estimation - Thanks @Subenle
• Fixed cygwin support
• Adding additional build environments for AppVeyor- Thanks @rkollataj
• Fix warnings which are caused by C style cast - Thanks @knowledge4igor
• Make short month names match in length - Thanks @berkus
• Fix typos in code and comments - Thanks @berkus
• Fixed missing i_formatter implementation
• Fix SPDLOG_WCHAR_TO_UTF8_SUPPORT wchar_t logging - Thanks @hestad
• Added formatter for unix epoch time in seconds (%E format flag) - Thanks @jasonbeach
• Compiler-dependent line numbering in SPDLOG_TRACE - Thanks @elelel
• Improved cmake and CMakeLists.txt - Thanks @mrpelotazo and @Lectem