livestreamer-twitch-gui is not hidpi-aware on linux

[Jujstme]

Description

The program does not determine if the desktop enviroment is HiDPI and, therefore, does not scale UI elements on HiDPI, thus rendering the GUI in a very small size (screenshot attached).

Expected / Actual behavior

The program is supposed to read the scaling settings for GTK+ applications, or at least provide a command-line option for manually setting up scaling.

Reproduction steps

1. start a desktop enviroment (eg. Gnome3) in a HiDPI display
2. set up scaling for your desktop enviroment (in Gnome3 this is done automatically, alternatively it's possible to set up scaling via gnome-tweak-tool)
3. start livestreamer-twitch-gui

Environment details (operating system, etc.)

Arch Linux x86_64
Linux kernel 4.6.4-1
Desktop enviroment Gnome3 3.20.2

Comments, logs, screenshots, etc.

[bastimeyer]

This is a known NW.js issue on Linux for the version that's being used here right now (0.12.3).
An upgrade to one of the new and rewritten NW.js versions (>=0.13.0) is still being blocked by some other issues. The upgrade will fix the scaling issue...
See the progress here: #275 (not final)

HiDPI scaling does work on OSX and Windows, though.