Replace all armor slot icons

[Montandalar]

I thought the new icons looked too much like clothes and a motorcycle helmet, so I got inspired and redid the set to look like actual armour.

• Helmet: a modified Neuicons icon from svgrepo.com
• Torso, legs, feet: entirely new icons by Blockhead (myself)

The following PNG optimisations were used on the images after Inkscape export:

pngquant 16 <filename> --floyd=0 --strip --speed 1
mv <filename>-or8.png <filename> # Assuming UNIX clobbering behaviour
oxipng -omax <filename>

The result is much smaller than an ordinary RGBA PNG export.

The --posterize option of pngquant is not recommended; I found it made the outline look way worse by undoing the smoothness of the anti-aliasing, and it set the main fill colour to the wrong shade of grey which was a bit too dark, so contrast was lost.

[wsor4035]

Much better than the current options, thanks