[core] CRI Extension for multiple schemes

[Jim Schaad <[e-mail]>]

I had a strange idea which both violates the entire concept of what CRI was
designed to do, but has the potential to solve some problems that have been
pushed onto the back burner.  

Given that we have broken down a URI into an array of items, and there has
been some desire to allow for some type of multiple schemes to be specified
for a URI, what happens if we put an array of schemes into a CRI.  This
would allow for something like the following:

[ ["coap", "coap+tls"], "example.com", ".well-known", "core"]

While one could additionally allow for an array of host/port information I
think that this would be a step to far.  One would need to "resolve" the
array of schemes down to a single item before it could be used as if it were
a URI but the ability to carry this information might be something very
useful.

Jim