* Add RareStyle qrc with the icons needed for comboboxes and spinboxes
* Add images as svg
* Refactor `styles` to `resources` since it contains more things now.
* Add stylesheet folders, each folder must contain a `stylesheet.qss` file.
* Don't use QResources, instead add an identifier in the qss url() which can
replaced later with the full path.
* Update RareStyle with SVG images for better quality.
