[modules] Add date, time, datetime

Add modules to show date, time and date and time. Instead of introducing
a "fancy" aliasing mechanism, simply implement time and date in terms of
datetime, by inheriting and overwriting selectively.

modules/date.py

@@ -0,0 +1,19 @@
+# pylint: disable=C0111,R0903
+
+'''Displays the current date and time.
+
+Parameters:
+    * date.format: strftime()-compatible formatting string
+    * date.locale: locale to use rather than the system default
+'''
+
+from .datetime import Module
+
+class Module(Module):
+    def __init__(self, config):
+        super().__init__(config)
+
+    def default_format(self):
+        return '%x'
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4