ObservationZoneClient: use nullptr instead of NULL
test/FaultInjectionPort: remove fake Port symbols

Just link TestDriver with the original Port.cpp.  After a few rounds
of refactoring a while ago, this is possible.
NEWS: prepare for 6.7.6
Device/Port: remove the "receive timeout" from API docs

The "receive timeout" has been obsoleted by the new method WaitRead().
Device/Port: move code to WaitAndRead()

Eliminate duplicate (and fragile) driver code.  Making the return
value unsigned (i.e. size_t), the API is somewhat more robust.
Device/Port: add a more complex FullRead() overload
Driver/LX: relax download timeout

Allow a memory section download to take up to 5 minutes.  The old
timeout was just one minute, which was not enough for long flights on
4800 baud.
Device/Port: Fix timeout error

In the Port::FullRead method, a potential endless loop could occur,
which was only interrupted by the supplied timeout value.
debian/rules: disable -fno-strict-aliasing

Our code aims to be aliasing-safe.  No need for this workaround.
.gitignore: ignore debian/xcsoar-doc
debian/rules: don't set CFLAGS

This is redundant and useless, as Makefile already sets this according
to the DEBUG setting.
debian/rules: remove the remaining CFLAGS declaration
debian/rules: add variable TARGET
debian/rules: append TARGET to TARGET_OUTPUT_DIR

Allow building multiple targets in one git clone.
debian/rules: parse "clang" from DEB_BUILD_OPTIONS
po: update Spanish translation
po: update Slovak translation
po: update Russian translation
po: update Croatian translation
po: update Danish translation