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

El issue no nombra archivos, tests ni puntos de entrada. Empieza por aclarar el comportamiento previsto de búsqueda y filtrado para listas largas de opciones de select, incluido en qué se diferencia de autocomplete; se considera terminado cuando los usuarios pueden encontrar y seleccionar una opción sin tratar el control como una entrada de texto libre.

Escrito por el modelo de indexación a partir del texto del issue.