Making Eclipse view different file extensions as PHP

FYI.

window > preference > general > content types.
Expand '▷Text' and you will find 'PHP Content Type'. Select that.
Then click 'Add' and insert your own extension.

Head to Window -> Preferences. Drill down to General -> Editors -> File Associations. From here you can add your extensions (e.g., *.module) and associate them with your preferred PHP editor.

Then restart Eclipse for the change to take effect.