Updates to the "stable" branch

[Alan DeKok]

  The "stable" branch now has brand new attribute encoding / decoding
routines.  The old code was awkward and confusing.  It had been
gradually extended over time to do VSAs, WiMAX attributes, and then the
new "extended" format:

http://tools.ietf.org/html/draft-dekok-radext-radius-extensions

  The new code is simpler and easier to understand.  Each function is
short: 100 lines maximum, with most being much smaller.  The functions
all have consistent names, take consistent arguments, and have a common
layout.

  The new code also has better support for WiMAX attributes.  The old
code would sometimes not be able to decode "long" WiMAX attributes.

  As a bonus, there is now a test tool which encodes/decodes RADIUS
attributes.  It's called "radattr" (in src/main).  A sample input file
is in src/tests/extended.txt.  More documentation and examples are in
the works.

  The goal is to add more tests, including tests for "bad" attributes.
The tests are simple enough that they can be verified by hand, but
complex enough to validate the new code.

  All of the existing attributes && VSAs *should* be encoded the same
(or better) than before.  If anyone is running the "stable" branch,
please try it, and let me know if there are any issues.

  Alan DeKok.