Implements settings in GUI

Changes:
* A few GUI elements now relies on settings (torrent status, curves)
* Fixed the hole at the beginning of the curve (it was due to starting the curve at an offset, instead of x=0)
* Removed the toolbar, it used deprecated methods, and was bigger than before, distorting the icons and blurring them
* Added a settings menu accessible from the settings button, settings are applied when clicking confirm, graphical changes are visible in real time ™