fix tcsh syntax

direct/src/configfiles/direct.init

@@ -3,7 +3,7 @@ ATTACH panda
 MODREL ETC_PATH etc
 DOCSH set parent=`dirname $DIRECT`
 DOCSH if ( ${?PANDA_ROOT} ) then
-DOCSH   setenv PYTHONPATH "$PYTHONPATH;"`cygpath -w "$parent"`
+DOCSH   setenv PYTHONPATH "${PYTHONPATH};"`cygpath -w "$parent"`
 DOCSH else
-DOCSH   setenv PYTHONPATH "$PYTHONPATH:$parent"
+DOCSH   setenv PYTHONPATH "${PYTHONPATH}:$parent"
 DOCSH endif