Apply cursorBlink via setOption

Fixes #478

demo/main.js

@@ -27,7 +27,9 @@ function setTerminalSize () {
 colsElement.addEventListener('change', setTerminalSize);
 rowsElement.addEventListener('change', setTerminalSize);
 
-optionElements.cursorBlink.addEventListener('change', createTerminal);
+optionElements.cursorBlink.addEventListener('change', function () {
+  term.setOption('cursorBlink', optionElements.cursorBlink.checked);
+});
 
 createTerminal();