cItem: Store custom data

[xoft]

I know it's gonna sound weird coming from me, but would it make sense to make the m_ItemMeta member contain a JSON object? It could be made transparent to Lua (so one could set "m_ItemMeta = LuaTable") and it would be much easier to work with on the C++-side.

One thing though - how will we decide what properties get parsed into their specific member variables, and what properties stay in the ItemMeta object?