[CM] Delimited strings in s7

[bil at ccrma.Stanford.EDU]

In case.scm I use #<...>, then object->string on the
#<undefined> object (and substring to get rid of the
brackets).  There are examples of regex strings in
that file.  But I'm not sure what you want here.
There are a lot of examples in lint.scm (line 23201).