Linux Mint logos: color optimization & mintwelcome

[mseveritt]

• mintwelcome by using the green template and centering the logo
• Changed colors of the Linux Mint logos according to linear gradients from green and white template with a very pleasing result :-). The form stayed unchanged as it came from hicolor. With a template for transparent backgrounds, I can try to reimplement them in a better way. It might be trivial, but can you provide such a template, please? It would be very helpful to have all standard linear gradients from the other templates present in it already vertically aligned.

[alvatip]

Great thanks, indeed, it looks better :+1: I will also add more templates to my "template" folder so it will be more complete