Synchronizing benchmarks.
Slightly boost performance by providing attributes move semantic.
Architecture planned for fast datetime string generator.
Datetime fast generator: several tests added.
Additional datetime generator test.
And additional test added.
Datetime generator: numeric month support added.
Datetime generator: numeric month day support added.
Datetime generator: numeric month day support added with new `%e` placeholder which means range [1,31].
Datetime generator: hour placeholder [0; 23] support.
Datetime generator: hour placeholder `%I` [1; 12] support.
Tests have been refactored.
Datetime generator: minute placeholder `%M` [0; 59] support.
Datetime generator: second placeholder `%S` [0; 60] support.
Additional test case added.
Implemented attachable stream.

Direct string manipulations (inserting integers and literal explicitly) gives significant performance boost over `std::stringstream`.
Inspired by boost::log I’ve decided to implement stream with ability to attach and get external string.
Also decomposition into subfiles done.
Benchmark updated.
Simple and fast integer generator algorithm implemented instead of using `boost::karma`.

Cause it is evil.
Datetime generator: support year `%C` placeholder for printing first two digits of year.
Datetime generator: implemented abbreviate month placeholder `%b`.

Also tests has been slightly refactored.