Require libzip, xslt and osm-gps-map in all builds

Conditional inclusion of libzip, xslt and osm-gps-map just
makes testing more cumbersome, since testers might lack
Subsurface features without knowing.

Signed-off-by: Henrik Brautaset Aronsen <subsurface@henrik.synth.no>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Disable non-functional Cochran code

There's no point in compiling this into the binary. It does not work.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Update Bulgarian, Dutch and Russian translations

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>