Create ViewController using keyboard and mouse in first-person perspective

**Original report ([archived issue](https://osrf-migration.github.io/ignition-gh-pages/#!/ignitionrobotics/ign-rendering/issues/50)) by Steve Peters (Bitbucket: [Steven Peters](https://bitbucket.org/%7B2ccfed09-18b8-4921-8d58-15ef01092802%7D/), GitHub: [scpeters](https://github.com/scpeters)).**

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# Summary

There are many games that use a first-person perspective with keyboard keys for moving forward, backward, left, and right (often WASD) and using the mouse to change the camera angle. This could be a nice alternative to the OrbitViewController in certain circumstances.

# Motivation

While visualizing tunnel envirnments for SubT, I have trouble using the OrbitViewController to inspect the inside of the tunnels. I think a first person view controller would be more natural for these types of worlds.

It would require responding to key events in addition to mouse events.

# Describe alternatives you've considered

We already have the Orbit View controller. Also some people like to use ESDF and other mappings instead of WASD, so perhaps the mapping could be configurable.