Clean up some markup cruft.  A number of the macros that take no
parameters (like \UNIX) are commonly entered using an empty group to
separate the markup from a following inter-word space; this is not
needed when the next character is punctuation, or the markup is the
last thing in the enclosing group.  These cases were marked
inconsistently; the empty group is now *only* used when needed.
diff --git a/Doc/lib/libdl.tex b/Doc/lib/libdl.tex
index 8d1220f..358f083 100644
--- a/Doc/lib/libdl.tex
+++ b/Doc/lib/libdl.tex
@@ -87,7 +87,7 @@
 Call the function named \var{name} in the referenced shared object.
 The arguments must be either Python integers, which will be 
 passed as is, Python strings, to which a pointer will be passed, 
-or \code{None}, which will be passed as \NULL{}. Note that 
+or \code{None}, which will be passed as \NULL.  Note that 
 strings should only be passed to functions as \ctype{const char*}, as
 Python will not like its string mutated.