added a TODO file and changed indentation in the .proto file

TODO

@@ -0,0 +1,12 @@
+TODO
+====
+
+* Fix the inappropriate use of Common Coin in the Byzantine Agreement protocol
+
+   This bug is explained in https://github.com/amiller/HoneyBadgerBFT/issues/59
+   where a solution is suggested introducing an additional type of message,
+   CONF.
+
+   There may be alternative solutions, such as using a different Byzantine
+   Agreement protocol altogether, for example,
+   https://people.csail.mit.edu/silvio/Selected%20Scientific%20Papers/Distributed%20Computation/BYZANTYNE%20AGREEMENT%20MADE%20TRIVIAL.pdf

proto/message.proto

@@ -1,53 +1,52 @@
 syntax = "proto3";
 
 message MessageProto {
-  oneof payload {
-    BroadcastProto broadcast = 1;
-    AgreementProto agreement = 2;
-  }
+    oneof payload {
+        BroadcastProto broadcast = 1;
+        AgreementProto agreement = 2;
+    }
 }
 
 message BroadcastProto {
-  oneof payload {
-    ValueProto value = 1;
-    EchoProto echo = 2;
-    ReadyProto ready = 3;
-  }
+    oneof payload {
+        ValueProto value = 1;
+        EchoProto echo = 2;
+        ReadyProto ready = 3;
+    }
 }
 
 message ValueProto {
-  ProofProto proof = 1;
+    ProofProto proof = 1;
 }
 
 message EchoProto {
-  ProofProto proof = 1;
+    ProofProto proof = 1;
 }
 
 message ReadyProto {
-  bytes root_hash = 1;
+    bytes root_hash = 1;
 }
 
 message ProofProto {
-  bytes root_hash = 1;
-  LemmaProto lemma = 2;
-  bytes value = 3;
+    bytes root_hash = 1;
+    LemmaProto lemma = 2;
+    bytes value = 3;
 }
 
 message LemmaProto {
-  bytes node_hash = 1;
-  LemmaProto sub_lemma = 2;
-
-  oneof sibling_hash {
-    bytes left_sibling_hash = 3;
-    bytes right_sibling_hash = 4;
-  }
+    bytes node_hash = 1;
+    LemmaProto sub_lemma = 2;
 
+    oneof sibling_hash {
+        bytes left_sibling_hash = 3;
+        bytes right_sibling_hash = 4;
+    }
 }
 
 message AgreementProto {
-  uint32 epoch = 1;
-  oneof payload {
-    bool bval = 2;
-    bool aux = 3;
-  }
+    uint32 epoch = 1;
+    oneof payload {
+        bool bval = 2;
+        bool aux = 3;
+    }
 }