bitcoin-cli: remove unneeded dependencies (only code movement)

Remove unnecessary dependencies for bitcoin-cli
(leveldb, berkelydb, wallet, RPC server)

Build system changes:
- split libbitcoin.a into libbitcoin_common.a, libbitcoin_server.a and
  libbitcoin_cli.a

Code changes (movement only):
- split up HelpMessage into HelpMessage in init.cpp and HelpMessageCli
  in rpcclient.cpp
- move uiInterface from init.cpp to util.cpp

src/util.cpp

@@ -95,6 +95,7 @@ string strMiscWarning;
 bool fNoListen = false;
 bool fLogTimestamps = false;
 volatile bool fReopenDebugLog = false;
+CClientUIInterface uiInterface;
 
 // Init OpenSSL library multithreading support
 static CCriticalSection** ppmutexOpenSSL;
@@ -1511,3 +1512,4 @@ void RenameThread(const char* name)
     (void)name;
 #endif
 }
+