Some doc updates and test update.

JetCore.txt

@@ -182,6 +182,10 @@ a variable named 'listing'.
 Use the comment tag to create a section in the jet script that can be
 used for making comments and is ignored by the jet reader.
 
+\section{expr}
+
+
+
 \section{for}
 
 Use the for tag to iterate a tag container for a logical number of

tests/testjet.jet

@@ -5,9 +5,11 @@
  <html>
  ---
  <set name="modified1" value="ABCD" />
- $[modified1]
- <set name="tohex" value="TOHEX" />
- $[modified1]
+ $[modified1;tohex]
+ <set name="tohex" value="tohex" />
+ $[modified1;$[tohex]]
+ <set name="complete" value="$[modified1];$[tohex]" />
+ $[complete]
  ---
  $[nonexistant]
  $[%HOME]