Support multi-line strings in defsystem metadata with FORMAT's tilde operator
Putting multi-line metadata into an ASDF defsystem, if you don't want hard line breaks, is ugly. We could get around this by adding support for tilde-newline sequences a la
Alternatively, we could just accept multi-line strings and reflow them, but that seems harder -- we would need to be careful to honor double-newlines.
Request for comments.