We'd like to pre-compute the interpolation if we can, so that we can run
this code properly... For now, we can't so it's a compile time error...
Hopefully we can remove this restriction in the future. The problem is
the string must be a constant, or it would be possible to switch it from
"%d %s" to "%s %d %d" or anything that changes the type signature.
Part of this was rotten, and not fully functional. This fixes the rot,
adds some tests, and improves the type checking that occurs when sending
and receiving values. In addition, a significant portion of this happens
at compile time.
There is still more work to be done here, but this should get us a good
chunk of the way for now.
Due to a limitation in the template library, we need to rename some
functions. It's probably worth looking into modifying this library or
finding an alternate version.
This continues the earlier patch that allowed resource names to be lists
of strings so that edges can now allow the same. This also includes a
new fancy test!
