python: upgrade and downgrade scripts

Author: yoff

python/ql/lib/downgrades/503c0516fba2e5da9570f00eb34ef43025ecb8fb/downgrade.properties

@@ -0,0 +1,6 @@
+description: Add new statements and expressions for the match syntax.
+compatibility: backwards
+py_exprs.rel: run py_exprs.qlo
+py_stmts.rel: run py_stmts.qlo
+py_patterns.rel: delete
+py_patterns_lists.rel: delete