Globals: Remove a bunch of Params() calls from main.cpp:

1) Chainparams: Explicit CChainParams arg for main:

-AcceptBlock
-AcceptBlockHeader
-ActivateBestChain
-ConnectTip
-InitBlockIndex
-LoadExternalBlockFile
-VerifyDB parametric constructor

2) Also pickup more Params()\. in main.cpp

3) Pass nPruneAfterHeight explicitly to new FindFilesToPrune() in main.cpp

src/rpcblockchain.cpp

@@ -562,7 +562,7 @@ UniValue verifychain(const UniValue& params, bool fHelp)
     if (params.size() > 1)
         nCheckDepth = params[1].get_int();
 
-    return CVerifyDB().VerifyDB(pcoinsTip, nCheckLevel, nCheckDepth);
+    return CVerifyDB().VerifyDB(Params(), pcoinsTip, nCheckLevel, nCheckDepth);
 }
 
 /** Implementation of IsSuperMajority with better feedback */
@@ -828,7 +828,7 @@ UniValue invalidateblock(const UniValue& params, bool fHelp)
     }
 
     if (state.IsValid()) {
-        ActivateBestChain(state);
+        ActivateBestChain(state, Params());
     }
 
     if (!state.IsValid()) {
@@ -867,7 +867,7 @@ UniValue reconsiderblock(const UniValue& params, bool fHelp)
     }
 
     if (state.IsValid()) {
-        ActivateBestChain(state);
+        ActivateBestChain(state, Params());
     }
 
     if (!state.IsValid()) {