add ttmodels

direct/src/showbase/ppython

@@ -57,6 +57,10 @@ if [ "$TTRADER" ]; then
     TTRADER=`cygpath -w $TTRADER`
     export TTRADER
 fi
+if [ "$TTMODELS" ]; then
+    TTMODELS=`cygpath -w $TTMODELS`
+    export TTMODELS
+fi
 
 # Export the proper home environment variable
 HOME=`cygpath -w $HOME`