code quality: making all the pixel based renderers `final`

as they are only a thin wrapper of `stbi` functions

src/renderers/BMPRenderer.hpp

@@ -6,7 +6,7 @@
 
 namespace massivedynamic {
 
-class BMPRenderer : public PixelRenderer {
+class BMPRenderer final : public PixelRenderer {
 	public:
 		BMPRenderer(const std::vector<bool>& pixels, size_t sourceSize, size_t targetSize) : PixelRenderer(pixels, sourceSize, targetSize) {}
 

src/renderers/JPGRenderer.hpp

@@ -6,7 +6,7 @@
 
 namespace massivedynamic {
 
-class JPGRenderer : public PixelRenderer {
+class JPGRenderer final: public PixelRenderer {
 	public:
 		JPGRenderer(const std::vector<bool>& pixels, size_t sourceSize, size_t targetSize) : PixelRenderer(pixels, sourceSize, targetSize) {}
 

src/renderers/PNGRenderer.hpp

@@ -6,7 +6,7 @@
 
 namespace massivedynamic {
 
-class PNGRenderer : public PixelRenderer {
+class PNGRenderer final: public PixelRenderer {
 	public:
 		PNGRenderer(const std::vector<bool>& pixels, size_t sourceSize, size_t targetSize) : PixelRenderer(pixels, sourceSize, targetSize) {}