* change hint for code checking edit field to indicate need for PIN
* add additional text about how code is constructed from OTP token and PIN
* change PIN preference label - add that it is mandatory
* add "followed by PIN" to text sent via SMS
SingleClickButton is a utility used in a number of modules and such should be
in core. While the app seems to built with the button in app, this wrong
structure should be fixed.
As the button is a UI element, the patch also moves the class to the package
info.nightscout.androidaps.utils.ui.
