make currency income support mumblereward

mods/currency/depends.txt

@@ -1,2 +1,3 @@
 default
 pipeworks?
+mumblereward?

mods/currency/income.lua

@@ -4,6 +4,9 @@ local timer = 0
 local function income()
     for _,player in ipairs(minetest.get_connected_players()) do
         local name = player:get_player_name()
+		if minetest.get_modpath("mumblereward") ~= nil then
+			if not mumblereward_players[name] then return end
+		end
 		local inv = player:get_inventory()
         inv:add_item("main", "currency:minegeld")
         minetest.log("info", "[Currency] basic income for "..name.."")