RxKeyboard Versions Save

• The visibleHeight's output is wrong when 'Reduce Motion' and 'Prefer Cross-Fade Transitions' are on fixed;
• Restricted number of touches to 1 that prevents keyboard unexpected behavior when user scrolls by multiple fingers simultaneously

Support RxSwift 6.0

Support Swift 5, RxSwift 5 and Xcode 10.2.

Support Carthage binary for Swift 4.2.1

Support for Swift 4.2 & Xcode 10

• Support Xcode 9.4 and Swift 4.1.2

• Support Swift 4.1

• Fix a bug that willShowVisibleHeight emits a value when hiding a keyboard (#52, @cpwhidden)

• Add RxKeyboardType protocol (#50)
• Add Xcode 9.2 support for Carthage