Replace main.overview._dash with the extension dash object.

This was made to make the appgrid animation come from the position of the
showAppsButton in the extension dash.
add pot file to gitignore
Update po files to be able to translate all strings.
update german translation
myDash: remove unused signals in appicon.

As per upstream commit 7ecb5af587af7ed892c6cfc5af0858a2acb04905:
The signal was last used in the pre-3.0 days, so we can stop dragging it along and just remove it.
Avoid Gjs Warning for function not alway returning a value.
Track structs of the main actor instead of the inner _box.

The border of the container was not taken into accoutn.
Add dock-position key in the settings in schema.

The dock will be positioned on all sides of the screen.
Add dock placement in pref.js.
Reverse left and right labels in the settings for rtl.
Reload the extension when positioning changes.
DashSlideContainer: implement sliding in all directions.
DockedDash: manage dock positioning on all screen sides.

Merge _updateYposition and _resetPosition. Now staticBox use the actor position
and not vice-versa as before.
myDash: myDashActor handles horizontal dash orientation.
myDash: dash main class handles different orientations.
Reverse left and right setting when in rtl.

I went for this convenction, so I just revert left and right when defining the
position if in rtl.
myDash: reverse left and right setting when in rtl.

I went for this convenction, so I just revert left and right when defining the
position if in rtl.
myDash: correctly handle drag and drop horizontally.
myDash: handle horizontal drag and drop in rtl.
Reserve space for the dock in the overview.