Remove unused code and add benchmark for consensus msg check

[rlan35]

1. Remove unused code and cleanup some outdated todos.
2. Add some benchmark code for consensus messages checking and signature verification. The benchmark result for doing 1000 times of each are:

Time required to sign 1000 sigs: 0.479827 seconds
Time required to unmarshall 1000 consensus msgs: 0.000662 seconds
Time required to marshal 1000 consensus msgs: 0.000453 seconds
Time required to deserialize 1000 sigs: 0.517965 seconds
Time required to hash 1000 messages: 0.001191 seconds
Time required to verify 1000 sigs: 1.444604 seconds

[JackyWYX]

The code looks good to me.