Deleted unnecessray qrw::IngameWindow::border.

Just use sf::RectangleShape::setOutlineColor/Thickness() to create a border ;)
namelessgui::Window now inherits from sf::RectangleShape.

This makes it possible to easily use RectangleShape methods like setSize() or setPosition(). Also the background is now available for every derived window.
Now setting background in qrw::IngameWindow in new way.

This is done by the sf::RectangleShape inheritance of namelessgui::Window.
Also qrw::DeployWindow now renders background properly.
Added namelessgui::SpriteWidget::setPosition(sf::Vector2f).
qrw::IngameWindow now using namelessgui::SpriteWidgets for plain squares.
Fixed defaultguitileset: attack and defense sprite were interchanged.
qrw::IngameWindow now completely relies on namelessgui widgets.

A custom draw() method for the IngameWindow is now redundant.
Merge branch 'gui-improvement' into dev