Currently, "everything can require everything". It's an unstructured
mess which sometimes causes problems.
This commit adds a tool that enforces a white-list of require() uses. It
uses depgraph to scan the source code and then each use of require()
that is found is checked. If any violations are found, the tool returns
a failure.
This tool is wired up to a new target "make check-requires" which is
included in "make check". Thus, Travis will run this.
Reference: https://github.com/awesomeWM/awesome/issues/1400
Signed-off-by: Uli Schlachter <psychon@znc.in>
Uli Schlachter