[Autocomplete] Should update input when focusing suggestion

[moshest]

Problem description

When I focus a suggestion, the autocomplete label remain as is. It's should update as the focused option and trigger onChange (see google.com for example).
You should create separate event for loading new suggestion only while typing.

Right now the events are confusing and make a lot of bugs.
Ie. when update searchText on onNewRequest it's get ignored because there is a menu.close(); timer that reset it with the chosen suggestion.

Steps to reproduce

Try it out on the docs.

Versions

• Material-UI: 0.15.2
• React: unrelated
• Browser: unrelated

[oliviertassinari]

Closed by #4783