GitLab

* added all necessary includes - fixed build/include_what_you_use error

* fixed the order of includes (build/include_order)

* Remove signed/unsigned integer compare warning with g++

The result of a right-shift of a signed negative number is
implementation-dependent.
cf. https://msdn.microsoft.com/en-us//library/336xbhcz.aspx

Fix #519
Fix #521