Added support for the new append method from NZBGet 13+

NZBGet 13 will probably be released in the next few days. This version has a new combined append method that supports both nzb urls and content. Also the return value was changed form boolean to integer (NZBID or error number).

The old methods append and appendurl are now Deprecated, so it's more future proof to add the new method now.
regardless of your personal viewpoint on how you think things should be done, you have to realize that we have our own preferences especially since we have to maintain the code / support it / deal with the problems if bugs arise. hence why we generally prefer code that is more readable and inline with the rest of the code in the file, im not asking for less efficient and we are more than happy to optimize things where we can (notice that ito has already addressed your concern and force pushed the change). for example we try to use pep8 guidelines (there are still several we dont follow though)

about the whole **ternary** format, I'm quite used to it in javascript world.. it just can get unwieldy quickly.
if you want to get truely code snobbish you can probably rewrite just about every line of python code into something that is shorter/smaller and go off on tangents about using shorter variable names/similar names so it can optimize better.. etc. writing shorter code doesnt always make it better.. 

if i have to spend more than a second looking at your line of code to understand or just read it (because of the length/overly complex/to much branching logic/etc) then there is an issue. ito and myself both felt the same thing as we both brought it up to be addressed (he just happen to do it himself while i mentioned it directly in the pull).

anyways, your variable concern with ito's change has been addressed.