File icons to include Debrief logo

[IanMayo]

We have the file-type icons:

• track_file.ai
• plot_file.ai
• sensor_file.ai

These icons aren't for use within the Debrief application. They're for use in the the Operating System (windows explorer, file manager, etc).

So, they need to add some Debrief branding. The Debrief logo is the "D" to the left of this image:
http://debrief.info/images/logo.png

We need to (somehow) include the D in the logo, so that users recognise it as a Debrief-related file.

The repo does include a D icon:
https://github.com/debrief/debrief-icons/blob/master/24/debrief_icon.png

You may wish to use that.

[IanMayo]

Defer this until we have a new Debrief icon/logo

[jsmarting]

Need voice discussion for clearance