added variables

tests/with_variables.expected

@@ -0,0 +1,4 @@
+4
+3
+6
+5

tests/with_variables.sl

@@ -0,0 +1,13 @@
+import ../stdlib/stdlib.sl
+import ../stdlib/io.sl
+
+word main
+    3 4 5 6
+    with a b c d in
+        b puti cr
+        a puti cr
+        d puti cr
+        c puti cr
+    end
+    0
+end

tests/with_variables.test

@@ -0,0 +1 @@
+python main.py tests/with_variables.sl -o /tmp/with_variables > /dev/null && /tmp/with_variables