组队邀请：同类邀请合并与过期失效

-- 错误：来一条存一条，永不过期
function pushInvite(teamId, from)
    save(teamId, from)
end

local invites = {}
local function pushInvite(teamId, from)
    local it = invites[teamId]
    if it then
        it.count = it.count + 1
    else
        invites[teamId] = {from = from, count = 1,
            at = os.clock()}
    end
    refreshBadge()
end
local function cleanExpired()
    for teamId, it in pairs(invites) do
        if os.clock() - it.at > 60 then
            invites[teamId] = nil
        end
    end
end