Add helper function pointerTypeToCursorId

I was kind of hoping for an explicit conversion operator on `PointerType` to convert to a `CursorId` struct, but sadly such conversion operators are not possible with `enum class`. A free standing function is I suppose close enough.

appOPHD/PointerType.cpp

@@ -5,13 +5,19 @@
 #include <NAS2D/Utility.h>
 
 
+constexpr NAS2D::CursorId pointerTypeToCursorId(PointerType pointerType)
+{
+	return NAS2D::CursorId{static_cast<int>(pointerType)};
+}
+
+
 void setCursor(PointerType pointerType)
 {
-	NAS2D::Utility<NAS2D::Renderer>::get().setCursor(NAS2D::CursorId{static_cast<int>(pointerType)});
+	NAS2D::Utility<NAS2D::Renderer>::get().setCursor(pointerTypeToCursorId(pointerType));
 }
 
 
 void addCursor(PointerType pointerType, const std::string& fileName, NAS2D::Vector<int> hotOffset)
 {
-	NAS2D::Utility<NAS2D::Renderer>::get().addCursor(NAS2D::CursorId{static_cast<int>(pointerType)}, fileName, hotOffset);
+	NAS2D::Utility<NAS2D::Renderer>::get().addCursor(pointerTypeToCursorId(pointerType), fileName, hotOffset);
 }

appOPHD/PointerType.h

@@ -7,6 +7,8 @@ namespace NAS2D
 {
 	template <typename BaseType>
 	class Vector;
+
+	struct CursorId;
 }
 
 
@@ -17,5 +19,7 @@ enum class PointerType
 };
 
 
+constexpr NAS2D::CursorId pointerTypeToCursorId(PointerType pointerType);
+
 void setCursor(PointerType pointerType);
 void addCursor(PointerType pointerType, const std::string& fileName, NAS2D::Vector<int> hotOffset);