Creating the canvas

[Gunes315]

As a painter I want to create a canvas in order to draw my pixel art

• [x] create a grid, in which every cell can be colored
• [x] ask users for width and height when creating a new canvas

[lisaaaa11]

Missing UI, size of canvas still adjusted as magic number, and very large pixels saved as magic number, problem will be solved, when UI is created!

[Deltapie-dev]

nicht fertig