Allow binary constants (e.g.: 0b01010)

- Add lexer and parser tests.
diff --git a/tests/test_c_lexer.py b/tests/test_c_lexer.py
index 7f69ac1..6d0b52d 100644
--- a/tests/test_c_lexer.py
+++ b/tests/test_c_lexer.py
@@ -75,6 +75,7 @@
         self.assertTokensTypes('0123456L', ['INT_CONST_OCT'])
 
         self.assertTokensTypes('0xf7', ['INT_CONST_HEX'])
+        self.assertTokensTypes('0b110', ['INT_CONST_BIN'])
         self.assertTokensTypes('0x01202AAbbf7Ul', ['INT_CONST_HEX'])
 
         # no 0 before x, so ID catches it