New CombineTokens prototype

Input params for negotiating enctype and level, and output params
for reporting back chosen parameters and error code.

Seed the error code registry with some potentially useful values.

Identity information is not a list.

Change-Id: I76e68fd4f626f43590a1e1115f64efb777d75511
Allow key version number to wrap at 16 bits

We only have 16 bits on the wire for the connection key version
number, but use the number as a 32-bit quantity.  Allow all 32 bits
to be used if both endpoints can locally track that quantity.

Change-Id: I1829b1740790d33f7056711192b6cfa44a012388
Tokens SHOULD NOT expire late

jhutz wants to be explicit about it.

Change-Id: I683334cd0502fd520a9d9a5f9d16b7cc9ea4574d
Add Security Consideration for token expiry

We have only a SHOULD NOT, not a MUST NOT, but be careful if you do.

Change-Id: I74ca6db8369e3fa93874eeb1454e425e58e7922f
Normalize whitespace

Death to carriage return.

Change-Id: I52226634b841addda8db8796edd464ae9a780eaa
reorder packet handling subsections

Put the packet handling descriptions in the same
order as the levels section; clear, auth, crypt.

Change-Id: Iba20ad6eed03782da22653c2b873e2993b996d29
artwork and clarification of RXGK_AUTH packets

Add artwork to show the memory structure for calculating
the MIC and the structure that is transmitted on the wire
for for the rxgk integrity level.

Change-Id: Id2af8c63dfd6efaf8384ce5d5c443221b8b79ade