OpenVPN Support Forum

I have done extensive research online and for the past few weeks tried several methods, but I am no expert on this matter at all.

I do believe my situation is very common for lot's of people:

Raspberry Pi 2 running OSMC (Debian) with Kodi as media center.
Besides Kodi I am running several other applications to sync my photoalbums and personal documents. Plus I am running a torrent client.

Goal:
I want the torrent client to only access internet via OpenVPN. All other applications should have normal access, bypassing VPN.

What would be the easiest and most common way to set this up? My goal is to explain it to others so I would prefer to either change .ovpn script or add a script that could be used by others with minimal changes. My ideas:
- ip tables, though I learned that this is a quick fix and not the best way.
- network name space, a seperate one for the applications that need to go via OpenVPN. Default one will have straight access to the internet. I could not figure this one out. Even though I came a lot further with help from a Dutch forum.

I am hoping someone can guide me in the right direction.

BUMP!! I can't imagine everyone who uses OpenVPN uses it for their entire system, all of their apps. That's simply not even possible for me. Especially on a mediacenter you need to be in your home country to watch local georestricted content.