first rev of release notes for 10.5.3.0

[Rick Hillegas]

I'm attaching a first rev of release notes for 10.5.3.0. Please send me 
your edits before 9:00 am San Francisco time on Monday August 10. These 
release notes are basically the 10.5.2.1 version with the following edits:

1) Changed 10.5.2.1 to 10.5.3.0
2) Added a separate table to describe the extra delta between 10.5.3.0 
and 10.5.2.1

3) Updated the Build Environment section with facts about my machine

Thanks,
-Rick