Capabilities are only supported on a session when both sides announce

Capabilities are only supported on a session when both sides announce
that capability. Change capa_neg_calc() to check always both the
ann(ounce) and peer capa struct to figure out what was negotiated.
This change affects route refersh and graceful restart (where before
setting the capability in the config to 'no' would not fully disable
the feature).
Also ignore and warn about unexpected route refresh messages.
OK benno@