Request colon-prefixed keywords in sexp macro

[samuel-jimenez]

Colon-prefixed keywords (:name compared with #:name) are common in Emacs and Common Lisp dialects.

Currently, the macro considers the colon character to be a separator, so splits tokens along the boundary.

e.g.,
sexp!((:name "Jane Doe" :street "4026 Poe Lane"))
produces (: name "Jane Doe" : street "4026 Poe Lane")

Permitting the sexp macro to accept colon-prefixed keywords will allow existing Common Lisp structured to be evaluated in a more natural manner with less manual editing.