Move selection inversion logic from setSelect to touchUpInside for mu…

…ltiple selection buttons; Break otherButtons retain cycle

Fix disconnected action responders in Swift example

Update Swift example file to use Swift 4

Add animation for button selection.

Added example for using with Swift.

Made APIs more Swift friendly.

Added support for RTL interface layout.

Updated API comments.

Improve button grouping performance

Add test case for grouping speed measuring
Fix build warning

Bump up version number.

Fix log bug in demo.