Adds several glass casting molds (block, slab, pane, 2x slab, and 6x pane), a recipe for a plain glass batch, patches the glass batches to act as glass blends for the glassmaking mod, and adds the required glass types.

I may eventually use the glassblowing mechanic for other items such as bottles or decorative blocks, but for now I enabled basic functionality.

When I am certain that things are working as expected without major bugs, I will probably disable the other ways of making glass or cooking/smelting the batches (some of this might already have been done as of v 1.0.0).