Add libkrad and krb5-otp

A new preauth module for the KDC and its support library.

The API of libkrad is not expected to be stable; its symbols are public
but we need a strict version dependency on the library.  Future changes
to the library will require close scrutiny as we will likely need to
adjust the versions in the symbols file with future changes.
We have pkgconfig files now

Install them (all) in libkrb5-dev.
Update symbols files

Synchronize with the output of dpkg-gensymbols.

This catches up with the kadm5 soname bump as well.

These do match the changes in upstream between 1.11 and 1.12.
Most removed symbols are internal symbols which were exposed due
to implementation details.  The implementation no longer requires
them to be exposed, so upstream does not expose them anymore.  There
are also some removed symbols in the kadm5 libraries, but those
are not considered stable interfaces by upstream (and we're making
a new package anyway).

I'm not sure why dpkg-gensyms decided to change its sorting (?) for
some of these symbols.
change version to 1.12+dfsg~alpha1-1

New upstream release, Closes: #694988, #697954
Build-depend on python-lxml, Closes: #725596
Remove Debian versions from symbols
Add myself to uploaders