Merge pull request #2 from nxg/master

Implement a/b/c... suffixes in references and citations, and create three-author fix
Add ident attribute

We would like to make sure that we can work out what version people
are downloading without necessarily having to put in explicit version
numbers. We do attempt to update the HISTORY field when we make changes
but in addition we now use a ident git attribute to automatically
embed the SHA1 in the file when it is checked out.

This fixes issue #3
Add LPPL license explicitly

Closes #4
Add year to presort.key -- same author but different year doesn't need a letter
Amend recommended \mniiiauthor command
A few more-or-less cosmetic changes
Merge commit 'upstream/master'