WebSandboxMC v1.4.0

• Add unbreakable/unplaceable blocks (bedrock), unbreakable_blocks config option (GH-46)

Update to NetCraft build 336:

• Update to emscripten 1.37.12 (satoshinm/NetCraft#123)
• Add F2 keyboard shortcut to take screenshots (satoshinm/NetCraft#119)
• Add support for reading .zip files of terrain.png (satoshinm/NetCraft#113)
• Add unbreakable blocks of infinite hardness, bedrock (satoshinm/NetCraft#131)
• Add /noclip command to walk through walls, in case you get stuck in bedrock (satoshinm/NetCraft#130)
• Fix possible out-of-bounds memory access in sign rendering (satoshinm/NetCraft#124)