phoc v0.21.1

This version requires wlroots 0.15.1 and recommends following wlroots patches:

  [ Guido Günther ]
  * xdg-surface: Fix crash on close with open popups
  * view: Improve doc strings for {get,set}_scale_to_fit
  * view: Allow to set activation token
  * view: Reindent and prefix view_activated
  * xdg-activation: Delay token submission

  [ Joerg ]
  * seat: Check if touch point is valid (Closes: #278)

  [ Sebastian Krzyszkowiak ]
  * desktop: Allow to pass NULL as sx and sy to view_at
  * render: Handle viewports and transforms when rendering to buffer
  * cursor: Consider root surface for layer-shell check in handle_touch_down
  * layer-shell: Adjust focus order to match rendering and input