"Include" option for resource filtering

[tomas-correia]

Currently, Phaser Editor lets the user specify the files and directories they'd like to filter from the project's file view.

But it would be very useful if it was possible to specify only the paths to be included instead of the ones to be ignored.

A possible example, in the phasereditor2d.config.json file:

{
    "include": [
        "game",
        "public/assets/game"
    ]
}

This would include both a game directory in the root, and a game directory under public/assets.