more sever scoping work.

tests/testscope.jet

@@ -1,8 +1,10 @@
 #!../jet-2.0
 <jet cgi="true" name1="localname" filterblanklines="true" trimlines="true">
  <set name="name2" value="localname2" scope="local" />
+ <set name="name3" value="global" />
  <set name="x" value="#[name1]" />
  localname=#[name1] 
  localname2=#[name2]
  localname through x=$[x]
+ <dump file="./dump.txt" />
 </jet>