Page indicator replaced with custom implementation

Replacing the UIPageControl with a custom implementation affords us significantly more flexibility as evidenced by the new features in this release.

Updates:

• Providing an initial page, dot size, and dot replacement image are all more reliable
• Faster load times with less jank
• Ability to replace any dot with a custom UIImage

let pagedView = SimplePagedView(
    imageIndices: [1: #imageLiteral(resourceName: "add")], // will replace the dot at index 1 with a UIImageView
    with: green, red, orange
)

let pagedView = SimplePagedView(
    // also supports negative indexing similar to Python. This will replace the last dot with a UIImageView
    imageIndices: [-1: #imageLiteral(resourceName: "add")],
    with: green, red, orange
)

Non-feature updates:
Check out the included example project and playground to try out other features 😄