Add iterator for concurrent threads.
Rename write_blocked to push_back.
Use pull_items_iterator for Renderclients.
Remove obsolete RenderClient.hpp.
Move to gua/concurrent.
Add concurrent namespace.
Apply clang-format.
Delete assignement operator and copy ctor.
Remove make_renderclient.
Merge pull request #28 from vrsys/feature/ctorsDoublebuffer

Feature/ctors doublebuffer