Light Multiplication

  Multiple light sources placed within close distance will have a greater combined brightness value, thus spreading light out to a much larger area.

  Currently, an annoying issue when building large creations is that you must place light sources everywhere. Having tons of torches placed everywhere can ruin the atheistic of a build. With this, you can be more smart (and creative) with your lighting. For instance, this would make large chandeliers actually light up your room.

  One way I imagined this could be implemented is brightness values would go beyond 15, but not actually get visibly brighter. For instance, perhaps 4 Glowstone Blocks placed together would increase the brightness to 20 (+2 per additional source). The light spreads out as usual and will only get darker when it falls below 15. This would work with all light sources, including natural ones like lava. There would have to be a limit, of course. You wouldn't want the lava in the Nether to multiply endlessly...

Here is a visual representation of what I am explaining:

As you can see on the left, the 4 Glowstone Blocks have a much larger spread of light. On the right is what we get normally.