Also -
1) Made note of the deprecation as well as the functions and
files that were removed earlier in upgrade.txt.
2) Added new functions to api.php to replace the deprecated ones
that were being used in unit tests.
3) Removed files that are no longer being used.
This is used by messaging system for sending/receiving message
to/from noreply or support user. message_send api will now use
core_user class to get noreply or support user and then
send/receive message depending on user state.