header include cleanup

- ensures alphabetical ordering for includes etc. in source file headers

src/txmempool.cpp

@@ -3,8 +3,9 @@
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include "core.h"
 #include "txmempool.h"
+
+#include "core.h"
 #include "util.h"
 
 #include <boost/circular_buffer.hpp>
@@ -644,4 +645,3 @@ bool CCoinsViewMemPool::GetCoins(const uint256 &txid, CCoins &coins) const {
 bool CCoinsViewMemPool::HaveCoins(const uint256 &txid) const {
     return mempool.exists(txid) || base->HaveCoins(txid);
 }
-