functionality to update gpx traces from files

[jamescr]

implements Upload gpx from file #36

[westnordost]

Thanks, looks fine! I have a few comments on that.

(There is also a bug in the code, but it will go away after doing the requested changes.)

[jamescr]

Thanks for the review, i applied the improvements to the code.

[westnordost]

Oh, don't forget to close the file input stream after it is read, otherwise the file will stay open.

Also in your own OSMTracker code of course.

I read up whether it is good practice to close the input stream already in our case in TracesApi::create but the general opinion is that an input stream should be closed at the level where it is created. In any case, it might be a good hint to explicitly state that in the javadoc, too.

[jamescr]

Thanks for the reminder to close the stream. Will add a line in the javadoc comment of the method.

[westnordost]

Great, thank you! There is one thing left that is also relevant for your implementation in OSMTracker. You'll likely want to use try-with-resources so that the file handle is always closed also if an IO exception occurs:

try (InputStream in = new FileInputStream(file)) {
  // ...
} catch (IOException e) {
  // ...
}

[westnordost]

Nice, thank you! Will release a new version today.