FAITriangleArea: add another condition for LargeLeft1

If delta_distance is negative, the arc doesn't exist and should be
skipped (TRAC #2632).
po: update Polish translation
po: update French translation
Screen/GDI: add assertions on DeleteObject()

To detect GDI memory leaks triggered by deleting GDI objects that are
still selected in a DC.
GDI/BufferCanvas: clear the HBITMAP in Destroy()

Avoid double free.
GDI/BufferCanvas: fix HBITMAP leak in Resize()

On older WinCE versions, these methods leak memory because they
destroy the HBITMAP without deselecting it from the HDC first.
TerrainDisplayConfigPanel: Change name of "Gaudy" terrain ramp to "Vibrant"

Vibrant does not carry the negative connotation of "Gaudy".
GDI/ContainerWindow: pass hCtl=nullptr to GetNextDlgTabItem()

Don't assume that the container itself is a control.  Fixes a focusing
problem on the Altair.
Form: focus the first client_area control

Fixes a problem on Windows CE: the dialog itself does not have the
WS_EX_CONTROLPARENT style, and therefore is not supposed to have
controls.  Windows (on the desktop) ignores this problem, but
GetNextDlgTabItem() on WinCE will fail and will return the dialog
handle itself.  Focusing it will put the keyboard focus nowhere, and
will disable all harware keys.  This is pretty fatal on the Altair.
po: update xcsoar.pot and *.po
release v6.5
Merge tag 'v6.5'

Conflicts:
	src/Dialogs/Settings/Panels/TerrainDisplayConfigPanel.cpp
Math/FastTrig: use sinetable for both sine and cosine

Reduces executable size by approx. 38 kb with virtually no overhead.