vibe.http.rest : example + URL

Change DDOC example for registerRestInterface into documented unit-test, reformat it for better readability.
Add method for URLRouter to check registered routes.
Implement standard way for URL formatting using stand-alone function
rest example: add termination event
rest example: add unittests to verify route paths
vibe.http.rest : full restyle

Adapt everything to vibe.d standard code style
Localize imports
Improve formatting where it helps readability
vibe.utils.meta.funcattr : add IsAttributedParameter
`funcattr` adjustments for usage with rest module

1) Add new calling overload in AttributedFunction so that it won't
try merging parameter and attribute type tuples when incoming and
target parameter type tuples match exactly. In that cases relevant
parameters are simply overwritten by attached attribute functions.

2) Add diagnostic that all attached InputAttribute functions conform
to stored argument list.

3) static imports added for qualified symbols
vibe.http.rest : add `funcattr` support
Add `funcattr` test case to vibe.http.rest suite

Also makes test suite exit upon both success and failure
Remove #line static assert