Add support for Chisel's IFacade Connected Textures API

Allows Chisel to render Facades of certain blocks with connected
textures.

@CrazyPants (author of Ender IO) recently added the IFacade API to [Chisel](https://github.com/Pokefenn/Chisel), allowing Ender IO Facades to work with Chisel's connected textures.

I maintain [ChiselFacades](https://github.com/Choonster/ChiselFacades), so I thought it would be nice if BC supported this API as well.

I've tried to make as few changes as possible, but I needed to change FacadeRenderHelper to use `Block#getIcon(iblockaccess, x, y, z, side)` instead of `Block#getIcon(side, meta)` so Chisel block facades use the connected texture icon instead of the normal one.

I also needed to add a custom IBlockAccess wrapper (like the one used in Ender IO's facade rendering code) so Chisel block facades display the correct metadata's texture. This wrapper could be moved to its own class if you feel that it doesn't belong in FacadeRenderHelper.