Remove extraneous borders from the window button xpms

Without this, if you change the background colour of the title bar,
the buttons have artefacts of the original background colour.
Adjust the title vertical position by 1 pixel

This makes the window titles look more vertically centred by my eyes.
It could just be down to the font and font size I am using though.
Reimplement original Orion using PNG files and Gtk colour.
Merge pull request #3 from ali1234/orion-orig-png

Original Orion as PNG files