Add filter support

filter.py

@@ -0,0 +1,14 @@
+_filters = []
+
+
+def apply_filters(ctx_msg):
+    filters = sorted(_filters, key=lambda x: x[0], reverse=True)
+    for f in filters:
+        r = f[1](ctx_msg)
+        if r is False:
+            return False
+    return True
+
+
+def add_filter(func, priority):
+    _filters.append((priority, func))