Work on rewrting the parser

And a unit test

tests/test_doc_entities.py

@@ -0,0 +1,24 @@
+import unittest
+from ptulsconv.docparser.doc_entity import HeaderDescriptor
+from fractions import Fraction
+
+
+class DocParserTestCase(unittest.TestCase):
+
+    def test_header(self):
+        header = HeaderDescriptor(session_name="Test Session",
+                                  sample_rate=48000.0,
+                                  bit_depth=24,
+                                  start_timecode="00:59:52:00",
+                                  timecode_format="30",
+                                  timecode_drop_frame=False,
+                                  count_audio_tracks=0,
+                                  count_clips=0,
+                                  count_files=0)
+
+        self.assertEqual(header.session_name, "Test Session")
+        self.assertEqual(header.convert_timecode(header.start_timecode), Fraction((59 * 60 + 52) * 30, 30))
+
+
+if __name__ == '__main__':
+    unittest.main()