Glass improvements

Hello,

This far, glass is a pretty nice building material, as everything in Unity version, 1000X better than the glass of the old Java version. There are some points, however, were it could improve, these being:

1. Add all the shapes of the other materials to glass as well, including the stairs. You know, they would be useful for decoration and sculpting. Moreover, one may wish to build a glass house as well.

2. Make the colors of painted glass more vivid, specially the darker tones. Sometimes, I think the colors on painted glass are a little pale, they could be more akin to the choosen color. This is specially true when it comes to dark colors, and black in particular. Once I made a 100% black glass expecting to get na insulfilm-like cover for the buildings, but all I got was a smooth fumê. It should have an opacity of 90%, let's say, so then we could get a true black glass and get smoother tones by using shades of grey.

Thas is it. Hope this helps make the game even better than it's becoming.