Enable/disable a "category" from options

[nathanwinder]

interface DebugOptions {
  categoryA: boolean | CategoryAOptions;
  categoryB: boolean | CategoryBOptions;
}
const DebugContext = createDebugContext<DebugOptions>(true, { categoryA: false })

this will result in all categoryB components running in debug mode while categoryA is not in debug mode.

Need to consider what this does if we support category merging #6 .