New Crosshairs

As discussed in !94 (merged), a set of new crosshairs, in different styles:

• Minimalistic
• Thin
• Traditional, with different stroke sizes (1px, 2px, 6px)
• Ornamental (small, medium, big)

I've appended them to the existing set. The menu only shows the new ones.
This way, the replacement does not break existing configs, and the legacy crosshairs remain accessible.