Migrate parts of prop. 156 to spec section for 0.9.49

Update I2NP spec for prop. 156
Clarify prop. 154 based on subsequent decisions made in prop. 156
Add more notes common structures spec about ECIES routers
Add notes in more places that tunnel ID must not be zero

i2p2www/spec/proposals/156-ecies-routers.rst

@@ -12,6 +12,19 @@ ECIES Routers
 .. contents::
 
 
+Note
+====
+Network deployment and testing in progress.
+Subject to revision.
+Status:
+
+- ECIES Routers implemented as of 0.9.48, see [Common]_.
+- Tunnel building implemented as of 0.9.48, see [Tunnel-Creation-ECIES]_.
+- Encrypted messages to ECIES routers implemented as of 0.9.49, see [ECIES-ROUTERS]_.
+- New tunnel build message is not yet defined or implemented.
+
+
+
 
 Overview
 ========
@@ -538,6 +551,9 @@ References
 .. [ECIES]
    {{ spec_url('ecies') }}
 
+.. [ECIES-ROUTERS]
+   {{ spec_url('ecies-routers') }}
+
 .. [I2NP]
     {{ spec_url('i2np') }}