Tidied code, added MidPoint to CompoundMark class

Compound Mark class is now constructed with a list of marks.
A mid point is created on its construction for use in Geo Calculations

#story[1124] #pair[wmu16, hyi25]

src/main/java/seng302/utilities/XMLParser.java

@@ -256,9 +256,9 @@ public class XMLParser {
             if (cMarkNode.getNodeName().equals("CompoundMark")) {
                 cMark = new CompoundMark(
                     XMLParser.getNodeAttributeInt(cMarkNode, "CompoundMarkID"),
-                    XMLParser.getNodeAttributeString(cMarkNode, "Name")
+                    XMLParser.getNodeAttributeString(cMarkNode, "Name"),
+                    createMarks(cMarkNode)
                 );
-                cMark.addSubMarks(createMarks(cMarkNode));
                 allMarks.add(cMark);
             }
         }