Added SQLite3 sink to the solution

Fixed issue #179 (Conflict with Boost.Asio) (by defining FMT_USE_WINDOWS_H=0 in format.h and preventing include of windows.h)

assigned nullptr to _database and _query_stmt upon flushing so that if flush gets called again, will not throw an exception

changed ctrs,variables,argsguments to match code style of spdlog, also removed columns mapping since there is no clean way of set column name dynamically on a prepared statement and changed query to use prepared statements

add msvc logging sink

Fixed header include problems.

Allow syslog logger on Mac OS X

use default move constructor/assignment for async_log_helper

Fixed issues with time zone UTC offset and daylight saving offset on Windows

- fixed false error (returning -1) in time zones without daylight saving (checking against TIME_ZONE_ID_INVALID instead of 0)
- accounts for daylight saving only when tm::tm_isdst is true
- accounts for standard time offset ([DYNAMIC_]TIME_ZONE_INFORMATION::StandardBias) in time zones that need it

Add zf_log to performance tests

On my machine I'm getting following results (real time, best of 3):
        1 thread   10 threads   100 threads
zf_log   0.466s     2.711s       2.608s
spdlog   0.747s     5.121s       5.376s

Added CLOCK_MONOTONIC trick