Replaced a hardcoded value with a constant from entities

git-svn-id: https://openser.svn.sourceforge.net/svnroot/openser/trunk@2949 689a6050-402a-0410-94f2-e92a70836424

lib/srdb1/schema/aliases.xml

@@ -103,8 +103,8 @@
     <column>
         <name>last_modified</name>
         <type>datetime</type>
-        <default>1900-01-01 00:00</default>
-        <description>Date and time when this entry was last changed.</description>
+        <default>&DEFAULT_DATETIME;</default>
+        <description>Date and time when this entry was last modified.</description>
     </column>
 
     <column>