Werner compil warning (#32)

* Replace int by size_t in for loops.

* Various dtor missing and some other warning fixes.

* fixed size_t vs int

* fixed size_t vs int

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Co-authored-by: Paddle <PaddleStroke@users.noreply.github.com>
Co-authored-by: Aik-Siong Koh <askoh@askoh.com>

OndselSolver/SparseVector.h

@@ -34,6 +34,7 @@ namespace MbD {
 				this->insert(std::pair<const int, double>(index, value));
 			}
 		}
+		virtual ~SparseVector() {}
 		double rootMeanSquare();
 		int numberOfElements();
 		double sumOfSquares();