serious scoping work unfinished.

tests/testscope.jet

@@ -1,5 +1,8 @@
 #!../jet-2.0
 <jet cgi="true" name1="localname" filterblanklines="true" trimlines="true">
+ <set name="name2" value="localname2" scope="local" />
  <set name="x" value="#[name1]" />
- $[x] $[x] 
+ localname=#[name1] 
+ localname2=#[name2]
+ localname through x=$[x]
 </jet>