Expand functionality

• AnchorLayoutBuider.build() now return UIView instead Self

• Add relative anchor operator like: above(bottomView:), below(topView:), after(leftView:), before(rightView:)

• Add multiplier operator on Constraint DSL

• Add "chainabilty" for UIDatePicker, UIPageControl, UIPickerView, UIStepper, UITabBar, UIToolBar

• Add KeyPath "chainabilty"

• Add frame\bounds chains

• Add closure-based api for adding gesture recognizers

• Add more desired UIControl actions like: onSwitchToggle, onTextChanged, onSliderChanged

• Add options to overwrite existed targets on new creation closure action

• Add UIStackView builder (such as Declarative StackBuilder)

• Change interitem spacing syntax in StackBuilder

• Fix Stack initializing error

• Add ViewStyle functionBuilder