Move CMedianFilter to timedata.cpp

Now that we no longer use the median filter to keep track of
the number of blocks of peers, that's the only place it is used.

src/test/timedata_tests.cpp

@@ -0,0 +1,38 @@
+// Copyright (c) 2011-2014 The Bitcoin Core developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+//
+#include "timedata.h"
+
+#include <boost/test/unit_test.hpp>
+
+using namespace std;
+
+BOOST_AUTO_TEST_SUITE(timedata_tests)
+
+BOOST_AUTO_TEST_CASE(util_MedianFilter)
+{
+    CMedianFilter<int> filter(5, 15);
+
+    BOOST_CHECK_EQUAL(filter.median(), 15);
+
+    filter.input(20); // [15 20]
+    BOOST_CHECK_EQUAL(filter.median(), 17);
+
+    filter.input(30); // [15 20 30]
+    BOOST_CHECK_EQUAL(filter.median(), 20);
+
+    filter.input(3); // [3 15 20 30]
+    BOOST_CHECK_EQUAL(filter.median(), 17);
+
+    filter.input(7); // [3 7 15 20 30]
+    BOOST_CHECK_EQUAL(filter.median(), 15);
+
+    filter.input(18); // [3 7 18 20 30]
+    BOOST_CHECK_EQUAL(filter.median(), 18);
+
+    filter.input(0); // [0 3 7 18 30]
+    BOOST_CHECK_EQUAL(filter.median(), 7);
+}
+
+BOOST_AUTO_TEST_SUITE_END()