Rename 'calendar.py' to 'cal', to present any confusion with the

Calendar class on case-insensitive platforms.

src/icalendar/__init__.py

@@ -1,6 +1,6 @@
 # Components
-from icalendar.calendar import Calendar, Event, Todo, Journal
-from icalendar.calendar import FreeBusy, Timezone, Alarm, ComponentFactory
+from icalendar.cal import Calendar, Event, Todo, Journal
+from icalendar.cal import FreeBusy, Timezone, Alarm, ComponentFactory
 
 # Property Data Value Types
 from icalendar.prop import vBinary, vBoolean, vCalAddress, vDatetime, vDate, \

src/icalendar/cal.py

@@ -37,7 +37,7 @@ class ComponentFactory(CaselessDict):
     'BEGIN:VEVENT\\r\\nDTSTART:19700101\\r\\nEND:VEVENT\\r\\n'
     
     >>> factory.get('VCALENDAR', Component)
-    <class 'icalendar.calendar.Calendar'>
+    <class 'icalendar.cal.Calendar'>
     """
     
     def __init__(self, *args, **kwargs):

src/icalendar/tests/test_icalendar.py

@@ -1,5 +1,5 @@
 import unittest, doctest, os
-from icalendar import calendar, caselessdict, parser, prop
+from icalendar import cal, caselessdict, parser, prop
 
 def test_suite():
     suite = unittest.TestSuite()
@@ -7,7 +7,7 @@ def test_suite():
     suite.addTest(doctest.DocTestSuite(caselessdict))
     suite.addTest(doctest.DocTestSuite(parser))
     suite.addTest(doctest.DocTestSuite(prop))
-    suite.addTest(doctest.DocTestSuite(calendar))
+    suite.addTest(doctest.DocTestSuite(cal))
     doc_dir = '../../../doc'
     for docfile in ['example.txt', 'groupscheduled.txt', 'small.txt']:
         suite.addTest(doctest.DocFileSuite(os.path.join(doc_dir, docfile)))