Merge pull request #295 from tribal-tec/master

Make header self-contained
Integrate CMake as git external, fix cppcheck errors
Partial CR #296
CR #296
Merge pull request #296 from eile/master

Integrate CMake as git external, fix cppcheck errors
Fix OS X build
Fix cppcheck on OS X
Merge pull request #297 from eile/master

Fix OS X build and cppcheck
Added two new window attributes to set the width and height.
Externally the attributes can only be set with the global config options/
environmental variables EQ_WINDOW_IATTR_HINT_WIDTH and
EQ_WINDOW_IATTR_HINT_HEIGHT. Each overrides the default window width/height
when no configuration file is provided.
Merge cleanups
Fixes for the compound error messages
Merge pull request #300 from bilgili/master

Fixes for the compound error messages
Fix #69: Introduce WindowSettings to decouple Window from SystemWindow

This also fixes a possible race while creating new system windows from
different threads as they modify the parent eq::Window directly.