BIP141: Commitment structure and deployment

Includes a fix by Suhas Daftuar and LongShao007

src/consensus/params.h

@@ -16,6 +16,7 @@ enum DeploymentPos
 {
     DEPLOYMENT_TESTDUMMY,
     DEPLOYMENT_CSV, // Deployment of BIP68, BIP112, and BIP113.
+    DEPLOYMENT_SEGWIT, // Deployment of BIP141 and BIP143
     // NOTE: Also add new deployments to VersionBitsDeploymentInfo in versionbits.cpp
     MAX_VERSION_BITS_DEPLOYMENTS
 };