Catch breaks/holidays during creation of lecture calendar

This addresses #8 (closed)

scripts/md2ical.py

@@ -23,6 +23,10 @@ def extract_lecture_dates(markdown_file, output_file):
     for table_entry in soup.findAll("tr")[1:]:
         date, title, lecturers = [e.contents[0] for e in table_entry.findAll("td")]
 
+        if lecturers == "-":
+            # Table entries without lecturer are considered to be breaks/holidays.
+            continue
+
         # Define lecture start/end. Needs to be adapated every semester!
         dt = datetime.strptime(date, "%Y-%m-%d")
         lecture_start = datetime(dt.year, dt.month, dt.day, 13)