hyphens in message names

[Ken Fox <fox@mars.org>]

We've now specified that protocol names are prefixed onto message
names with '-'.  I'd like to also specify that message names within a
protocol cannot contain '-'.  For example, unless I misunderstand the
current system, a dispatcher upon getting 'mcp-negotiate-can' is faced
with the following possible dispatch paths.  (p) designates a protocol
or subprotocol and (m) indicates a mesasge dispatch.

root(p) -> mcp-negotiate-can(m) 
root(p) -> mcp -> negotiate-can(m)
root(p) -> mcp(p) -> negotiate(p) -> can(m)

If we outlaw - in message names, this becomes exactly one possible
dispatch path:

root(p) -> mcp(p) -> negotiate(p) -> can(m)

which simplifies dispatchers and makes it more clear exactly what is
going on and where calls go (or try to go).

--Ken