Feature: Add the dashed style. (#594)

examples/dom/border_style.cpp

@@ -11,6 +11,7 @@ int main(int argc, const char* argv[]) {
 
   auto document = vbox({
       text("borderLight") | borderLight,
+      text("borderDashed") | borderDashed,
       text("borderHeavy") | borderHeavy,
       text("borderDouble") | borderDouble,
       text("borderRounded") | borderRounded,

examples/dom/separator_style.cpp

@@ -16,6 +16,12 @@ int main(int argc, const char* argv[]) {
           hbox(text("left"), separatorLight(), text("right")),
       }) | borderLight,
 
+      vbox({
+          text("separatorDashed"),
+          separatorDashed(),
+          hbox(text("left"), separatorDashed(), text("right")),
+      }) | borderDashed,
+
       vbox({
           text("separatorHeavy"),
           separatorHeavy(),