Replace old C headers with the C++ ones (#1099)

src/CalcManager/pch.h

@@ -21,6 +21,6 @@
 #include <vector>
 #include <winerror.h>
 #include <iostream>
-#include <math.h>
+#include <cmath>
 #include <random>
 #include <iomanip>

src/CalculatorUnitTests/pch.h

@@ -21,7 +21,7 @@
 #include <windows.h>
 #include <collection.h>
 #include <ppltasks.h>
-#include <assert.h>
+#include <cassert>
 #include <concrt.h>
 #include <string>
 #include <bitset>

src/GraphControl/pch.h

@@ -17,7 +17,7 @@
 #include <concrt.h>
 #include <future>
 #include <memory>
-#include <assert.h>
+#include <cassert>
 #include <functional>
 #include <string>
 #include <sstream>