Improve image compression

Converted 24-bit images to 8-bit and then ran:

oxipng -o max -Z --preserve -s --fix --alpha -r --zi 255 .

and

zopflipng --lossy_transparent -y --iterations=500 --filters=01234mepb --lossy_8bit input.png input.png

Before: 2,31 MB (2.430.037 bytes)
After:  1,30 MB (1.374.207 bytes)

Signed-off-by: XhmikosR <[email protected]>

Author: XhmikosR