Support SwiftPackageManager

Adding the support of SPM #62, thanks @TwoDollarsEsq

Support Swift 5

• Support Swift 5
• Fix the tracking when the value is equal to the max

Features

• Add option to stop thumb looping over the min/max value
• Add offset thumb option, to draw the thumb inside or outside the circle

Support Swift 4.2 version

2.1.0

2.0.0

• Add Carthage support
• Support multiple number of rounds, allowing to create slider same as Apple bedtime slider (12h clock with two rounds)
• Add backtrack inspectable properties
• Add shadow track color and offset inspectable attributes
• Remove distance from default slider

1.1.0

• Fix Swift 3.1 warnings

0.1.0

Initial release.