Changed definitions int, long, and float to use seconds since the

epoch, rather than days since 1901.  This makes

  DateTime(float(d))==d

lib/python/DateTime/DateTime.py

@@ -84,7 +84,7 @@
 ##############################################################################
 """Encapsulation of date/time values"""
 
-__version__='$Revision: 1.22 $'[11:-2]
+__version__='$Revision: 1.23 $'[11:-2]
 
 
 import sys,os,regex,DateTimeZone
@@ -371,12 +371,6 @@ class DateTime:
             the gmt value of the time.time() float represented in
             the local machine's timezone.
         
-            Note that there is a small inconsistency here.  When
-            a DateTime is converted to a number (e.g. with float()),
-            the value returned is the number of days since Jan 1,
-            1901. This means that DateTime(float(d)), where d is a
-            DateTime does not return a DateTime that is equal to d.
-        
           - If the function is invoked with two numeric arguments,
             then the first is taken to be an integer year and the
             second argument is taken to be an offset in days from
@@ -1206,7 +1200,7 @@ class DateTime:
     def __add__(self,other):
         """A DateTime may be added to a number and a number may be 
            added to a DateTime;  two DateTimes cannot be added."""
-        if type(other)==InstanceType:
+        if hasattr(other,'_t'):
             raise self.DateTimeError,'Cannot add two DateTimes'
         o=float(other)
         d,t,tz=(self._d+o),(self._t+(o*86400.0)),self._tz
@@ -1264,16 +1258,16 @@ class DateTime:
                      self._day+self.time)*100)
 
     def __int__(self):
-        """Convert to an integer number of days since Jan. 1, 1901 (gmt)"""
-        return int(self._d)
+        """Convert to an integer number of seconds since the epoch (gmt)"""
+        return int(self._t)
 
     def __long__(self):
-        """Convert to a long-int number of days since Jan. 1, 1901 (gmt)"""
-        return long(self._d)
+        """Convert to a long-int number of seconds since the epoch (gmt)"""
+        return long(self._t)
 
     def __float__(self):
-        """Convert to floating-point number of days since Jan. 1, 1901 (gmt)"""
-        return float(self._d)
+        """Convert to floating-point number of seconds since the epoch (gmt)"""
+        return float(self._t)
 
 
 class strftimeFormatter: