Introduce absolute forms for service and module URIs

[bruno]

[current state: proposal, still thinking about this, feedback welcome]

Currently the syntax for the service and module URIs is
service:/restservice-name/path
module:/path

thus with one single slash after the colon.

We have noticed two things:

• when resolving relative paths containing "../", for the service protocol it doesn't make sense to go past the part of the path containing the restservice name
• a service or module URI cannot be interpreted by itself, only in the context of a module. This is no problem, but for errormesages and the like it would be convenient if we have some absolute form.

Proposed forms:

Normal:
service://restservice-name/remainder-of-path
module:/resource-path (= same as now)

Module-absolute:
service://restservice-name@module-id/remainder-of-path
module://module-id/resource-path

Note that, for reasons of encapsulation, we don't want to enable any module to access any (possibly private) restservice or resource of any other module. While this syntax would be recognized, it will only be allowed that the module-id is equal to the one of the current module, thus making it rather purposeless to specify the module-id.

[mpo]

beyond 0.4 scope