CirclingWind: reset after time jump of 30s or more

Override Validity::FixTimeWarp()'s default of 5 minutes, which is too
much for circling.
WindEKFGlue: move "-1" to right-hand side
test/RunWindEKF: format time stamp
Revert "WindEKFGlue: move "-1" to right-hand side"

This reverts commit 7cf4ab3b0424ccc16eba951d0480cab65238ce66.  It was
bad because I forgot to consider the fabs().
test/RunWindEKF: don't print quality

Not used by WindEKFGlue.
test/RunWindEKF: enable CirclingComputer

This is necessary for the "black hole" test.
WindEKFGlue: move counter into the class

Eliminate global variable.  Clear the counter in Reset() to be sure we
never emit a result with less than 10 samples.
Computer/AutoQNH: Also calculate QNH for replays
Widget/RowFormWidget: Fix SaveValue() for non-metric unit settings

Fixes trac issue #2771.
SafetyFactorsConfigPanel: Fix "Safety MC" setting for non-metric unit setup
po: update Polish translation
BasicComputer: always compute airspeed when possible.
Dialogs/WindSettingsPanel: add option to add "Clear" button
InfoBoxes/Wind: use WindSettingsPanel

Replaces WindEditPanel and WindSetupPanel.  These two have not seen
the recent usability improvements.  By replacing WindSetupPanel, its
"external wind" bug (not working at all) is eliminated (#2770).
GlueMapWindow: don't draw pan info over north arrow

TRAC #2765.
release v6.6_beta2
TraceComputer: activate contest trace with a small number of points

The contest trace will be used for the triangle solver. The number of
points is limited by the computing power, because the triangle solver's
runtime can be up to about O(n^2.2).

Assuming Win CE devices are slow is safe.
TaskComputer: use contest trace for triangle solver
OLCTriangle: reset branch and bound tree if n_points < 3
OLCTriangle: check tree size after pruning

Fixes a segfault in some cases