Introduce Specification class

.. used to create a 'specification' against which we match
   a rideitem when plotting etc.

.. so rather than passing an array/vector/list of data when
   calling a plot, we pass the 'specification' to use instead.

.. the plots themselves should now iterate across the shared
   ride cache only plotting the items that pass the specification.

.. this should reduce memory usage and increase performance.

src/Specification.cpp

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2014 Mark Liversedge (liversedge@gmail.com)
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "Specification.h"
+#include "RideItem.h"
+
+Specification::Specification(DateRange dr, FilterSet fs) : dr(dr), fs(fs) {}
+Specification::Specification() {}
+
+// does the rideitem pass the specification ?
+bool 
+Specification::pass(RideItem*item)
+{
+    return (dr.pass(item->dateTime.date()) && fs.pass(item->fileName));
+}
+
+// set criteria
+void 
+Specification::setDateRange(DateRange dr)
+{
+    this->dr = dr;
+}
+
+void 
+Specification::setFilterSet(FilterSet fs)
+{
+    this->fs = fs;
+}