Add startTangent and endTangent of CGPath.
Add startTangent and endTangent of CGPath.

hejunbinlan/SwiftGraphics,sdesimone/SwiftGraphics,rhcad/SwiftGraphics,Pretz/SwiftGraphics,Pretz/SwiftGraphics,rhcad/SwiftGraphics,SheffieldKevin/SwiftGraphics,marinehero/SwiftGraphics,marinehero/SwiftGraphics,rhcad/SwiftGraphics,hejunbinlan/SwiftGraphics,Pretz/SwiftGraphics,slightair/SwiftGraphics,SheffieldKevin/SwiftGraphics,sdesimone/SwiftGraphics,sdesimone/SwiftGraphics,marinehero/SwiftGraphics,hejunbinlan/SwiftGraphics,slightair/SwiftGraphics,slightair/SwiftGraphics,marinehero/SwiftGraphics,SheffieldKevin/SwiftGraphics,Pretz/SwiftGraphics,hejunbinlan/SwiftGraphics,sdesimone/SwiftGraphics,rhcad/SwiftGraphics,slightair/SwiftGraphics