Component load pr

[Y-Less]

Two small improvements to component loading:

1. Adds "exclude": to the top level of the JSON so you can explicitly not load certain components. Especially when testing I would frequently have to list all the components and remove one just to load all but one:

{
    "exclude": [ "Vehicles" ]
}

2. Gives a message when a component listed in "components": doesn't exist:

{
    "components": [ "Checkpoints", "GongZones", "Variables" ]
}

Now gives an error instead of silently failing.

[Y-Less]

P.S. I now want to write a GongZones component...