#63 auto-convert outline and wp to string

[PreFab Software]

Given the expression:
aString + anOutline
I'd like the latter automatically coerced to a string.

Same for aWPText.

e.g. for my web framework, I prefer to keep templates
and various snippets in outlines so I can edit them.
On the scripting site, it's easier to refer to them
directly rather than explicitly coerce to a string all
the time.

The error msg is: "This operation is not supported for
outline values. If you intended to take its address,
use the '@' operator."

A general note: Frontier almost always "does the right
thing" with datatypes, including lots of other
automatic coercions for concatentation (+). I think
this change falls in that spirit.