iOS Dynamic Framework improvements

[marmelroy]

Hello,

I am using Keyframes in a Swift-only project and encountered a number of issues when integrating it as a dynamic framework - the most significant being the fact that the project didn't have a public header.

This PR solves the following:

• Adding a public header to improve usage as a dynamic framework.
• Fixing the example app so that it doesn't need a bridging header.
• Fixing a missing init warning on KFVectorView.
• More controversially perhaps, renaming the framework to the correct case (i.e. Keyframes instead of keyframes).

[marmelroy]

Thanks for the quick feedback @LazyChild. I made three of the four requested changes.

[marmelroy]

So the real issue was the way that the Swift sample project was set up. It's now fixed and the PR uses #import <Keyframes/[public class].h> everywhere.