This replaces boost::thread and most mutexes and condition variables with
std equivalents. It also adds support for std lock types to the strictest_lock
type trait.
This significantly, although not completely, reduces the dependency on
Boost.Thread.
Refs https://github.com/boostorg/log/issues/232.
included into the size limit.
The max_size method on the stream buffer will now attempt to truncate
the attached string on the character boundary.
Fixed character boundary detection for multibyte encodings.
Clean up the overflow flag and the max size limit after the formatter
has completed.
Added a test for the max_size decorator.
Cleaned up some includes and reduced the dependency on Boost.Thread.
