Feature request: search/filter in select

#### Bug, feature request, or proposal:
Feature request

#### What is the expected behavior?
User able to search/filter the options in a select

#### What is the current behavior?
User must scroll the select to find the desired option

#### What is the use-case or motivation for changing an existing behavior?
When there is a long list of options, it's not easy to find an option

#### Which versions of Angular, Material, OS, TypeScript, browsers are affected?
Latest Angular Material as of 12 July 2017

#### Is there anything else we should know?
This is different from autocomplete, autocomplete is a free-text input field.

I haven't found anything in Material Design related to this, but this could be an important feature

The issue does not name any files, tests, or entry points. Start by clarifying the intended search and filtering behavior for long select option lists, including how it differs from autocomplete; done means users can find and choose an option without treating the control as a free-text input.

Written by the indexing model from the issue text.