Added a --runway= option which can be used in conjunction with the --airport=
option to specify a starting airport + specific runway. If you don't specify
a runway, you get the one that's closest to your specified (or default)
heading.
Now the options can be localized as well. This adds a slight problem for
the --language options, but not that much (worst case, the strings are
loaded twice consuming some more memory). I tried to be as accurate as
posiible when copying the options texts, but there might be some
mostakes left.
