CompareProjection: use TinyHypot() instead of SmallHypot()

This is about very tiny values, and SmallHypot() fails due to
rounding.  This affects the cached terrain bitmap, and caused the
terrain to not update until the map was moved a lot.
MapWindow: check both projections in OnPaint()

Both projection objects are used, therefore we must check both.  Fixes
an assertion failure that occurs when the user zooms while the
DrawThread runs for the first time.
GlueMapWindow: fix multi-touch pan gesture (#2684)

Call PanTo() instead of EnterPan(), because the latter discards the
current pan location.
TriStateJob: new wrapper utility class
ExternalLogger: fix bogus error message after pressing "Cancel"

Suppress the error popup when the user has pressed cancel.
Driver/FLARM: use FlarmDevice::Send()

Use this wrapper method everywhere.
Driver/FLARM: work around a Garrecht TRX-1090 firmware bug

See code comment.  Fixes TRAC #2745, #2749.
Android/BluetoothHelper: show name instead of MAC address

Backport from 6.7.
Driver/LX: faster LXNAV Nano detection over Bluetooth

Check the Bluetooth peer name.  If it begins with "LXNAV-NANO-" then
we can be sure it's a Nano.  This fixes part of #2819 which is due to
delayed Nano detection.

Backport from 6.7 to improve Nano compatibility.
Wind/WindEKF.cpp: tweak initial covariance fix #2961

At the initialisation of Kalman filters, the filter needs estimates of the
initial covariance (read as uncertainty) of the hidden states.  Due to
the nonlinear nature of the algorithm, in certain conditions if the
estimates are asserted to be more accurate than they actually are, the
algorithm can become unstable.  This is what was occurring with #2961; lag
introduced by the update order drives the scale factor towards zero or infinity,
with consequent effects on wind estimates.

Increasing the initial uncertainty of scale factor produces stable results
and equivalent wind estimates (that is, it does not appreciably slow down the
convergence).

This must go in the running for the competition for smallest bug fix
(one character) with most obscure reason behind it.
NavDijkstra: increase MAX_STAGES to 32

This is necessary to support large tasks, which are allowed since
commit 264336ce.
release v6.6.4
Merge tag 'v6.6.4' into v6.6.x

Conflicts:
	NEWS.txt