proposal: consistent message format

[Dick Hardt]

Problem:
Direct and indirect messages have different formats. This adds  
complexity for the developer. Specifically:
	- some messages have parameters start with "openid.", others are  
bare keywords.
	- some messages have the namespace parameter, and others don't
		openid.ns="http://openid.net/signon/2.0"

Proposal:
	= All openid protocol parameters start with "openid."
	= All messages have the parameter
		openid.ns="http://openid.net/signon/2.0"

Benefits:
	+ consistent for developers
	+ all messages are versioned

Drawbacks:
	- code changes