Simple function that will recursively extend lua tables.

table-extend.lua

function extend(table1, table2)
    for k,v in pairs(table2) do 
		if (type(table1[k]) == 'table' and type(v) == 'table') then
			extend(table1[k], v)
		else
			table1[k] = v 
		end
	end
end

this is pretty old, but if any one else stumbles upon it... the method needs to return table1 and then it seems to work as expected