This commit introduces 3 new log level. Thoses are:
+ NOTICE, which is a bit worse that INFO, but still not a warn.
+ ALERT, for case worse that critical.
+ EMERG, application is unusable.
With those 3 log levels, spdlog now has all log level accepted by
the syslog() system call.
in file included from ../include/spdlog/sinks/../formatter.h:57:
../include/spdlog/details/pattern_formatter_impl.h:308:26: warning: absolute value function 'abs' given an argument of type 'rep' (aka 'long') but has parameter of type 'int' which may cause truncation of value [-Wabsolute-value]
auto secs_diff = abs((duration_cast<seconds>(diff)).count());
^
../include/spdlog/details/pattern_formatter_impl.h:308:26: note: use function 'std::abs' instead
auto secs_diff = abs((duration_cast<seconds>(diff)).count());
^~~
std::abs
1 warning generated.
