rename point => icon

src/renderer/painter.cpp

@@ -63,7 +63,7 @@ void Painter::setupShaders() {
     lineShader = std::make_unique<LineShader>();
     linejoinShader = std::make_unique<LinejoinShader>();
     patternShader = std::make_unique<PatternShader>();
-    pointShader = std::make_unique<PointShader>();
+    iconShader = std::make_unique<IconShader>();
     rasterShader = std::make_unique<RasterShader>();
     textShader = std::make_unique<TextShader>();
     dotShader = std::make_unique<DotShader>();