16e3cd380a Clarify include recommendation (practicalswift)
6d10f43738 Enforce the use of bracket syntax includes ("#include <foo.h>") (practicalswift)
906bee8e5f Use bracket syntax includes ("#include <foo.h>") (practicalswift)
Pull request description:
When analysing includes in the project it is often assumed that the preferred bracket include syntax (`#include <foo.h>`) mentioned in `developer-docs.md` is used consistently. @sipa:s excellent circular dependencies script [`circular-dependencies.py`](50c69b7801/contrib/devtools/circular-dependencies.py) (#13228) is an example of a script making this reasonable assumption.
This PR enables automatic Travis checking of the include syntax making sure that the bracket syntax includes (`#include <foo.h>`) is used consistently.
Tree-SHA512: a414921aabe8e487ebed42f3f1cbd02fecd1add385065c1f2244cd602c31889e61fea5a801507ec501ef9bd309b05d3c999f915cec1c2b44f085bb0d2835c182