Added more generic respondToSwipe method

Deprecated SwipableView.respondToSwipe(like: Bool, opacity: Float) in favor of SwipableView.respondToSwipe(direction: SwipeDirection, distance: Float).

Add Swift version to podspec file

Add Swift version to podspec file + format & lint the code. Thanks @manucheri!

Version 0.4.2 - Made it possible to call respondToSwipe programatically

Made respondToSwipe method open and only requiring a direction.

The reason is that we might want to call it programatically, for example when pressing a button.

Version 0.4.1 - SwipableViews are undoable by default

Changed default implementation of isUndoable in SwipableView class.

Version 0.4.0 - Unlimited undo

Adds undo functionality for all swipe directions

Adds swipe history

Version 0.3.1 - Fix issue with custom card sizes

Update version to fix custom size support

Version 0.3.0 - Swift 4 support

• Upgrade to Swift 4
• Add support for custom stack sizes

Version 0.2.0, supporting vertical swipes

Added support for vertical swipes