GUI refinement

[Cydhra]

Refine the optics of GUI screens by using non-placeholder graphics for fluid-/energy bars, tab icons, progress bars, etc.

• [x] finalized content-bar textures
• [ ] finalzed progress-bar textures
• [ ] finalized configuration tab layouts (side, redstone mode, etc)
• [ ] finalized tab icons
• [ ] #72
• [ ] everything has tool tips