Ignoring empty string entries to not generate broken .strings file

Here is the pull request. 
I've never used git much before, good opportunity to learn. Hope I've done everything right.

There's a lot more lines changed then needed, this is because I also fixed the inconsistent indentation.
These are the critical lines:

    if(key.length == 2) {
      printf("Warning: Ignoring empty key entry\n");
      continue;
    }

Need to check key.length == 2, because the input string includes the ", so an empty string is "\"\"".
Also added a warning message. Would be nice if it also reported file and line number, but I didn't have time to understand the parse code enough to do the changes safely.

Cheers,
Olof