Switch to a scaleable vector graphics logo

Jaime Villate did make a svg version of the maxima logo. I like the concept behind SVG and SVG images have the advantage of being still sharp when some window manager, dock or the gnome-shell logo overlay extension scales them to bigger sizes or they appear on a retina display so I tried to make a scaleable logo my favourite GUI frontend for the program.

Like Jaime Villate I tried to stick near to the one of the original logos I saw on the screen most of the time - and I added the code that makes wxMaxima use the new logo to all places I am sure the new logo will work.
Since logos are important and the answer to the question if a logo is good is highly subjective I won't be too disappointed if this patch isn't applied, though.