Reset pressure barrier timeoutId after animation; shorten timeout from 300 to 100.

Reset needed because of Window Manager warning: log level 8:
Source ID ### was not found when attempting to remove it.
Remove pressure barrier when app is in fullscreen.

Pressure barrier was preventing the mouse from accessing the 2nd monitor when an app
was in fullscreen mode.

Connect to global.screen in-fullscreen-changed. UpdateBarrier now checks if actor is visible.
NOTE: Main.layoutManager sets the actor visible property to false when in fullscreen.
Check that wsWindowAppsBox is valid before attempting to access child object.

Clicking on the thumbnail caption without a taskbar threw errors.
Reimplement 'Require click to show the dock when window maximized' option.
Update compiled schema.
dockedWorkspaces: Rename property monitorsChanged to updateRegion.
dockedWorkspaces: Refresh thumbnails to adjust for workarea when dock-fixed is enabled.

We use updateRegion=true to wait for the regions to update (layoutManger->updateRegions)
before refreshing thumbnails. We also force thumbnails to refresh on animateIn complete
in case the dock is hidden when dock-fixed is enabled.
Initialize removeBarrierTimeoutId and remove Mainloop entry when the dock is destroyed.

This is just a precaution. I didn't notice any issues to cause this change.
Dash-to-dock integration: use enter-event and leave-event instead of hover.

Hover sometimes leaves the workspaces dock showing after hovering over the dash, entering 
apps overview mode, and then moving away from the dash.  Using enter-event and leave-event
prevents this.

I also added a check for dash hover even when the dash is triggered by pressure. This prevents 
the dash from showing the workspaces dock on a fullscreen app.
Thumbnail window images/clones are not properly representing maximized or fullscreen app 
windows that use Client Side Decorations.

To Duplicate:
Open gedit text editor (prime example of CSD app). Move it around on the desktop and you'll notice that the thumbnail window images stay in sync (that's good).

Now, move gedit to the center of the desktop and maximize it. Press <super> to enter activities overview (or just mouse over to the dock) and notice how the thumbnail window image is positioned slightly to the top-left leaving the workspace background to be seen on the right-bottom edge of the thumbnail. Now, unmaximize gedit and notice how the thumbnail window image is in a different position than the actual window on the desktop.

Move gedit to the center of the desktop again. Hit F11 to enter fullscreen mode. Hit <super> key to enter the activities overview and see how the thumbnail window image is positioned to the right leaving the workspace background to show on the left side of the thumbnail.
Updated metadata for Gnome 3.12 v20 release.
Updated installation zip for Gnome 3.12 v20.
Fix bugs relating to hoveringDash flag.

Bugs:
Fix bug where workspaces dock is shown in overview (apps view) due to hoveringDash flag. 
Fix bug where dock gets stuck and won't dodge windows because of hoveringDash flag.
Updated installation zip for Gnome 3.12 v20.
Merge branch 'develop'