updated SRFI-109 (extended string quasi-literals)

[Per Bothner <per@xxxxxxxxxxx>]

I've made a number of changes to SRFI-109.  Until the editors
have a chance to upload it, you can read it at:
http://per.bothner.com/tmp/srfi-109/srfi-109.html

I've settled on the &name[initial-exp]{text} syntax, which
is a hybrid of the XML syntax (in using & rather than @)
and the Scribble syntax (in using a single prefix character
rather than #&, and in the use of brackets/braces).

There are some changes in the S-expression mapping, along
with a rationale.  Specifically:
  &{abc&[exp1 exp2]def}
is now translated to:
  ($string$ "abc" |$[$| exp1 exp2 |$]$| "def")

I've added support for indentation adjustment (&|),
comments (&#|comment|#), and continuation lines (&-).

I've implemented these changes in Kawa, along with the
beginnings of a SRFI-64-style testsuite.  (The Implemention
section has links to both.)
--
	--Per Bothner
per@xxxxxxxxxxx   http://per.bothner.com/