Rename Slave to Host

The role of a slave as a host for Factorio servers is not well reflected
in its name and has caused confusion among users.  Rename slave to host
to better reflect its role as a host of Factorio servers.

packages/host/lua/export/clusterio_api.lua

@@ -0,0 +1,73 @@
+local function is_array(t)
+	local count = 0
+	for k in pairs(t) do
+		if type(k) ~= "number" then
+			return false
+		end
+		count = count + 1
+	end
+
+	for i = 1, count do
+		if not t[i] then
+			return false
+		end
+	end
+
+	return count ~= 0
+end
+
+-- no game.table_to_json here :(
+local function table_to_json(data)
+	if type(data) == "number" then
+		if data == math.huge then return "1e500" end -- Inf is not representable in JSON, but 1e500 will overflow to it.
+		if data == -math.huge then return "-1e500" end
+		if data ~= data then return "0" end -- NaN is not representable in JSON, treat as 0 instead.
+		return string.format("%.17g", data)
+
+	elseif type(data) == "string" then
+		data = data:gsub('([\x00-\x1f\\"])', function(match)
+			return "\\u00" .. string.format("%02x", match:byte())
+		end)
+		return '"' .. data .. '"'
+
+	elseif data == nil then
+		return "null"
+
+	elseif data == true then
+		return "true"
+	elseif data == false then
+		return "false"
+
+	elseif type(data) == "table" then
+		local r
+		if is_array(data) then
+			r = {"["}
+			for i=1, #data do
+				r[#r+1] = table_to_json(data[i])
+				r[#r+1] = ","
+			end
+
+			-- overwrite last comma, empty table is an object
+			r[#r] = "]"
+
+		else
+			r = {"{"}
+			for k, v in pairs(data) do
+				r[#r+1] = table_to_json(tostring(k))
+				r[#r+1] = ":"
+				r[#r+1] = table_to_json(v)
+				r[#r+1] = ","
+			end
+			r[#r + (r[#r] == "," and 0 or 1)] = "}"
+		end
+
+		return table.concat(r)
+	end
+end
+
+local clusterio_api = {}
+function clusterio_api.send_json(channel, data)
+	data = table_to_json(data)
+	print("\f$ipc:" .. channel .. "?j" .. data)
+end
+return clusterio_api