virtual destructor for LinearOperator

Grid/algorithms/LinearOperator.h

@@ -542,6 +542,7 @@ public:
       (*this)(in[i], out[i]);
     }
   }
+  virtual ~LinearFunction(){};
 };
 
 template<class Field> class IdentityLinearFunction : public LinearFunction<Field> {

README.md

@@ -1,7 +1,8 @@
-# Grid [![Teamcity status](http://ci.cliath.ph.ed.ac.uk/app/rest/builds/aggregated/strob:(buildType:(affectedProject(id:GridBasedSoftware_Grid)),branch:name:develop)/statusIcon.svg)](http://ci.cliath.ph.ed.ac.uk/project.html?projectId=GridBasedSoftware_Grid&tab=projectOverview) 
-
+# Grid 
 **Data parallel C++ mathematical object library.**
 
+[![Teamcity status](https://ci.dev.dirac.ed.ac.uk/guestAuth/app/rest/builds/aggregated/strob:(buildType:(affectedProject(id:GridBasedSoftware_Grid)),branch:default:true)/statusIcon.svg)](https://ci.dev.dirac.ed.ac.uk/project/GridBasedSoftware_Grid?mode=builds) 
+
 License: GPL v2.
 
 Last update June 2017.