starthawaii: Set xcursor paths

Otherwise the cursor theme won't be found when Hawaii is installed in
an unusual location such as /opt/hawaii.
client: Fix referencing padding from style for dialogs
client: Don't set with and height for AuthenticationDialog

Size is automatically detected.
client: Dialogs singleton

All dialogs will be created and managed by this singleton.
Currently it only has the authentication dialog.
client: Turn PolicyKit agent into a service

Make the PolicyKit agent available to the QML world as a service.
Also emit signals that will be received by the Dialogs singleton which
in turn will show, hide and setup the authentication dialog.
client: Move ShutdownDialog to Dialogs singleton
client: Rename Dialogs to DialogsSingleton and add qmldir
client: Register daemons and singletons
client: Set HawaiiShell as parent for services

This avoids services getting deleting as soon as they are not used.
server: Kill the right client PID

We save the client PID when we launch it, kill that instead of
finding it from the client resource.
client: Dialog size now considers margins too
client: Remove unnecessary margin item in Dialog

We can remove the margin item if we account for margin in the main
layout.
client: Point default property in Dialog to data

This lets us mix visual items with resources just like we do with Item.
client: Create ShutdownDialog every time
client: Remove filler item in ShutdownDialog
client: Decrease timer before updating the label in ShutdownDialog

Since we trigger the timer at start we need to start counting from 70
and decrement before updating the label.
server: Enable surface destruction animation for InOutSurfaceEffect

This code path can be enabled only for Weston 1.3 or better.
server: Make sure dialog surface is mapped before starting the animation
server: Disable shell dialog animations for now

We have problems with authentication dialog. The surface is supposed
to progressively resize to full size but this doesn't happen.

Here's what happens:

 - As authentication is requested a dialog is created.
 - The modal overlay fades in and we see a really small rectangle
   centered on the output, that should be the authentication dialog.
 - Hitting tab will give password field focus and this updates the
   buffer resulting in the dialog being resized to full size.

Expected result: dialog resizes to full size progressively.

Works with the shutdown dialog though...

I decided to disable the animation for now so that we can finally
release Hawaii 0.2!