Change setImmediate default to true for most components

[vaadin-bot]

Originally by @Legioth

---

Change setImmediate default to true for most components. Using immediate false is seen as an optimization.

---

Imported from https://dev.vaadin.com/ issue #8029

[vaadin-bot]

Originally by @mstahv

---

AFAIK this mostly matters for fields. Why not make it something like this and put it already into 6.8:

Boolean immediate;

public void setImmediate(boolean b){
   immediate = b;
}

public void isImmediate() {
   if(immediate != null ) {
      return immediate;
   }
   return getEventRouter().hasListeners(ValueChangeListener.class); // or component specific d
}

Developers can then most often forget the immediate flag and things will just work. But normal forms are as well optimized as before (no extra server visits). Explicitly defined values work as before.

[vaadin-bot]

Originally by @mstahv

---

Just wrote a small demo app with our latest tools V7, TouchKit 3 and JPAContainer 3. Two things that annoyed me most:

1. Fix Grid focusable test. #8029
2. Slider component resets value when disabled #4513

I can't believe how these were left out from V7. Both are cheap and safe to fix and would make a huge difference in developer experience. And would concern most Vaadin developers, unlike fancy JS integrations or CSS tools.

Plz fix ASAP!

[vaadin-bot]

Originally by @mstahv

---

"Fixed" in a way that shouldn't cause unintentional extra server visits to server, but still work seamlessly in vaadin/vaadin@8af8d2f