po: update xcsoar.pot and *.po
dlgWaypointEditor.cpp: Changed "Landpoint" to "Landable" to stick with established terms.
po: update Polish translation
po: update German translation
Startup: stop audio vario after stopping MergeThread

The MergeThread may call AudioVarioGlue::SetValue() after the
PCMPlayer object has been destructed.  This commit reorders the two
destruction calls to avoid this race condition.
Form/List: wrap HasEPaper() in UsePixelPan()
Form/List: don't start kinetic movement on DragMode::CURSOR

DragMode::CURSOR switches to DragMode::SCROLL as soon as the finger
has moved above a certain threshold.  Kinetic movement shall only
start when that has already happened.
Form/List: disable kinetic movement on e-paper

This doesn't work well because e-paper screens are slow.
Form/List: obey UsePixelPan() in MoveOrigin()

Fixes the mouse wheel and the scroll bar arrow buttons on e-paper
screens which could not scroll to the last item (part of TRAC #3082).
Form/List: use item-aligned scroll bar on e-paper

Fixes using the scroll bar handle to scroll to the last item (second
and last part of TRAC #3082).
InfoBoxLayout: no double-width InfoBoxes at the vario column

Commit 1292c62 assigned the remaining pixels to the last InfoBox
column, however this did not consider a vario gauge on the last
column (TRAC #3079).
Form/ScrollBar: use regular integers instead of PixelScalar
InfoBoxLayout: add border between vario and InfoBoxes
PageActions: add API documentation
PageActions: export GetConfiguredLayout()
BigTrafficWidget: auto-restore page layout only if not FLARM page

If auto-closing the FLARM page is configured as soon as no traffic is
received anymore, call PageActions::DeferredRestore() only if the page
we're about to restore is not a FLARM page.  That would mean that we'd
be calling PageActions::DeferredRestore() over and over, but the
TrafficWidget instance will stay, but will never call Update(),
leaving the last visible traffic on the screen forever (TRAC #3030).
MapDisplayConfigPanel: hide "max auto zoom distance" if auto zoom is disabled
GlueMapWindowDisplayMode: inline a few internal methods
GlueMapWindow: move code to RestoreMapScale()
PageState: split map_scale into cruise_scale and circling_scale

Synchronise with MapSettings::{cruise,circling}_scale and let
GlueMapWindow::RestoreMapScale() apply the new page's scale.  This
fixes distinct page zoom in conjunction with circling zoom (TRAC
#2907).