+ add UIComponent

+ add parent classes like UIComponent as base of all and UIContainer for holding multiple components
+ add UILayer for switching displayed UI easily
+ add UIFocusManager to manage focus independently to ensure, that only one component at a time can be focussed
+ add UILayout, but without functionality yet
+ add basic actual components: Button, Label and TextField
+ add interfaces to keep new components similar: TextHolder (for components, that have some kind of text stored and displayed) and ValueHolder (for progressbars and number inputs etc)

…Component for more flexible usage

+ add UIAlignment just test some things out
* some modifications

+ add an optional layoutinfo variable into component for additional information used in layouts

+ add RadioBoxGroup
+ add SingleSlider
+ add field for visibility to UIComponent

+ update CheckBox, add constructor

+ add ValueHolder to RadioBoxGroup

Move ecs package to component package, since this isn't a true ECS.
Move Text to ui package

+ improve constructor of UIComponent

…he parent

+ add AbsoluteLayout as default layout
+ add getter for directly accessing the absolute coordinates of a component

Grid layout works now (was nullptr exc before) but it could use a lot of help

Loading .tmx files into a Tilesystem
Demonstrated in this video: https://youtu.be/vgvssK_OPso