avoid just spinning forever when selected quality doesn't exist

[rakslice]

Addresses the spinning forever when there is no stream for the selected quality mentioned in #292

• if the selected stream or VOD doesn't have the quality from the settings (e.g. the last quality manually set with the dropdown), try "source" instead
• if for whatever reason we still get a null URL, don't try playing the null UR, and log an error

[QuLogic]

Please, can you make a new release with this fix? It's reeaally annoying, because the quality dropdown doesn't even show up.

[rakslice]

Note that you if you want to try a commit on windows without waiting for a new release, you can just go to the Appveyor automated build job (https://ci.appveyor.com/project/alamminsalo/orion/branch/master -- you can find it from the Build Passing button in the Readme), pick x86 or x64, and go to the artifacts section and download the exe (which is the installer) from that build.

[rakslice]

But hopefully @alamminsalo can put up a new release soon?