Don't just list games and mods in the Customize section, make separate tabs

[Casimir]

As Wuzzy pointed out in another issue, it's hard to maintain the list of games and mods in "Customize", the choice is also arbitrary.

Now that ContentDB is coming with the new version it might be better and easier to link to the various sections there. For example no "Customize" tab but one for "Games" one for "Mods" and one for "Texture Packs" which would link directly to Games, Mods, Texture Packs.

The pros are:

• Everything up to date
• No arbitrary choice to be made
• No manual changes to the website needed
• Out of the box screenshots and good presentation
• Looks more professional than links in a manual composed list to some form threads
• Separate tabs promote customization better than a tab that says Customize

Let me explain the last point. Currently when you visit minetest.net you see one game called Minetest. The tab Customize reads as if you could tweak some things here and there. With separate tabs it becomes clear that Minetest is an engine and we have games and mods and more. Because MT is about mods we should give them the place they deserve.