Various changes to make the docs look nicer. Add a new doc_author class.

Various changes to make the docs look nicer.  Add a new doc_author class.

The one thing that someone (misha?) should look at is fixing doc_code so that it sizes to fit the code instead of going to the right margin all of the way.  Fixing it at a particular number of pixels was just wrong. :)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13668 91177308-0d34-0410-b5e6-96231b3b80d8