Include directive for router configuration

[bruno]

In case of large routing descriptions, it would be nice to be able to split them up in multiple files which are combined by means of inclusion mechanisms.

Some thoughts about this:

• to some extend less urgent, because:
  • modules already provide one level of dividing up
  • it is also possible to instantiate multiple routers with different configurations within one module, though that will lead to multiple restservices to export and hence is not transparent to the outside world
  • things like JAX-RS decentralize the routing in other ways
• consider to have not only fixed includes, but also runtime-determined includes. Cfr. to map:mount in Cocoon: in the source of the to-be-included file, variables can be used which can only be resolved in the context of a request.
• and also look at other features of Cocoon's map:mount like strip-prefix, pass-through and check-reload