Replace splash screen

New splash screen uses Makigas logo. Also, splash screen is now
scaled using a different way. Instead of scaling it so that it
takes the entire screen size, splash screen is displayed centered.
In case screen is bigger, an integer scaling factor has been
applied. Image will be scaled by an integer value, such as 2, 3
or bigger, before being centered if it's still known that it will
fit.
Corrects gameplay from rendering blue

It seems that I forgot to add a background color to gameplay screen.
After my last commit, which also changed the background color of the
splash screen to #003399, I forgot to set the background color of
the other screens to any other value. As a result, space field in
gameplay screen was also being rendered #003399.

IDEA: Should I make gameplay background color dynamic too?