sml-page pretty printer

Print the UID in curly brackets to show it is some sort of identifier.
simplify and streamline parser

Simplify and streamline the parser. Instead of iterating over the body
twice (with complex rules the second time), every time a blank line
appears in the body of the message during read-in call the function
TRANSFORM-BODY on the last block of text.

In PARSE-SML-TABLE don't use recursion. Mapping results in more
readable code.
use macros sparingly

Use macros sparingly... in this case, not at all. Why was that a
macro?
Merge branches 'simplified-parser' and 'minor-changes' into testing
Merge branch 'testing'

Summary of changes:

Add an initarg for the `body-form' slot.

Add UID to pretty printer.

Calculate the structured body (aka: body-form) during read-in. This
should be slightly faster on long messages.

Change `<sml-render' to a normal function.