Improved HUD textures

[ShadowHunter12]

I have made a few modifications to the default textures for the primary and secondary crosshair, along with the radar targets. The goal of the change was to make the main crosshair be slightly more visible and have a single pixel wide slot in the very center that lines up with corresponding lines added to the radar target. With this change it becomes a lot easier to percisely target the cores of ships that are beyond visual range. Hope some people find this useful. Text above the textures are their original file names, they must replace the ones in starmade/data/image-resource

crosshair-simple-c-gui-

crosshair-c-gui-

hud-target-c-4x4-gui-

Good hunting.