'XMonad.Layout.Spacing': compatibility tweaks
'XMonad.Layout.Spacing': compatibility tweaks

* All the backwards-compatibility functions now accept `Int` rather than
  `Integer`: `spacing`, `spacingWithEdge`, `smartSpacing`,
  `smartSpacingWithEdge`, `setSpacing`, and `incSpacing`. Work done by
  @LSLeary.
* Introduce the new functions `setScreenWindowSpacing`,
  `incScreenWindowSpacing`, `decScreenWindowSpacing`. Unlike their
  original `setSpacing`, `incSpacing` counterparts, these refresh no
  more than once. Requires `sendMessages` from my PR of
  `XMonad.Actions.MessageFeedback`. Suggestion by @LSLeary and
  implemented so any combination of messages can be sent without
  triggering unnecessary refreshes.

xmonad/xmonad-contrib,xmonad/xmonad-contrib