icon/SudokuGameIcon.svg "ubuntu orange image" not centered and not .svg

Hello again,

Here is two issues with the icon/SudokuGameIcon.svg in the "About" tab:

     - The three "ubuntu orange image"s on the middle line aren't centered in their blocks. If you look in one block, at the spaces: between the left border and the first "u" on one side, and between the last "u" and the right border on the other side, you will see that these two spaces aren't equal, showing you that the image isn't centered. Also I find these two spaces too small making the image in the tab not looking so well.

     - The three "ubuntu orange image"s aren't .svg making the tab picture strange looking.

This is an opinion though

Thanks again for your great app.