Remove unnecessary dependencies for bitcoin-cli

This commit removes all the unnecessary dependencies (key, core,
netbase, sync, ...) from bitcoin-cli.

To do this it shards the chain parameters into BaseParams, which
contains just the RPC port and data directory (as used by utils and
bitcoin-cli) and Params, with the rest.

src/chainparamsbase.h

@@ -0,0 +1,52 @@
+// Copyright (c) 2014 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_CHAIN_PARAMS_BASE_H
+#define BITCOIN_CHAIN_PARAMS_BASE_H
+
+#include <vector>
+#include <string>
+
+/**
+ * CBaseChainParams defines the base parameters (shared between bitcoin-cli and bitcoind)
+ * of a given instance of the Bitcoin system.
+ */
+class CBaseChainParams
+{
+public:
+    enum Network {
+        MAIN,
+        TESTNET,
+        REGTEST,
+
+        MAX_NETWORK_TYPES
+    };
+
+    const std::string& DataDir() const { return strDataDir; }
+    int RPCPort() const { return nRPCPort; }
+    Network NetworkID() const { return networkID; }
+protected:
+    CBaseChainParams() {}
+
+    int nRPCPort;
+    std::string strDataDir;
+    Network networkID;
+};
+
+/**
+ * Return the currently selected parameters. This won't change after app startup
+ * outside of the unit tests.
+ */
+const CBaseChainParams &BaseParams();
+
+/** Sets the params returned by Params() to those for the given network. */
+void SelectBaseParams(CBaseChainParams::Network network);
+
+/**
+ * Looks for -regtest or -testnet and then calls SelectParams as appropriate.
+ * Returns false if an invalid combination is given.
+ */
+bool SelectBaseParamsFromCommandLine();
+
+#endif