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

该 issue 没有指定任何文件、测试或入口点。首先明确长 select 选项列表的预期搜索和筛选行为，包括它与 autocomplete 的区别；完成的标准是用户无需将该控件当作自由文本输入框，就能找到并选择一个选项。

由索引模型根据 Issue 内容生成。