Fix login and high dpi screens

Fixes those two annoying bugs.

Fix login

For some reason the JS never got loaded when it was in it's own file, therefor I moved it into the HTML where it gets called.

Also when a session id on the server was expired or something, you weren't able to log out, there is now code which fixes that.

Fix arrows navigation + AppImg

This is basically the same as the last one but there are some bugs fixed so the CI could build a AppImg.

Fix arrows navigation

This is a bugfix release which makes the arrow navigation workable again.

Menu- and Scrollbars

Small bugfixes:

• prevent horizontal scrollbars
• MenuBar now hidebar

Overflow fix

• Small nightmode fixes
• Overflow for <pre>
• Precompiling QML

Nightmode contrast

This changes the colors in the nightmode a bit so they are more visible with more contrast.

Nightmode and Fullscreen

In this release we are getting a night mode which makes it easier to read in the dark and a full screen mode too. There are also a lot of bugfixes like the one scrolling bug in the sidebar.

One more important change is the change of the license, I decided to change it from BSD to GPL v3.

Bugfix for Qt 5.7

I have no idea why, I think it might be some timing issues while
initializing the webengine, but when using runJavaScript() in
the WebEngineView without referencing it with the id of that
QML object it just throws the error that it doesn't know what
runJavaScript() is. When we use the ID then it just works
for some reason.

Version 2.1.1 - Webengine

This is using the new QWebengine for showing the HTML