modify code to suppress or fix warnings in gcc and clang (#41)

* first fix to start branch PR

* explicit conversion from sizet to int

* Array.h and DiagonalMatrix.h

* many sizet to int conversions

* removed some unused variables and added expl overrides

* removed many unused parameters

* more typing

* even more

* last of the easy changes

OndselSolver/IntegratorInterface.cpp

@@ -69,7 +69,7 @@ void IntegratorInterface::postFirstStep()
 	//this->checkForOutputThrough(integrator->t);
 }
 
-void IntegratorInterface::interpolateAt(double tArg)
+void IntegratorInterface::interpolateAt(double)
 {
 	//"Interpolate for system state at tArg and leave system in that state."
 	assert(false);