call `L` with multiple argumens.

Now `L("a","b","c")` produce `{"a"}`
I fix this like:

``` lua
local function LL_impl(...)
    local res = {}
    for i = 1, select('#', ...) do
        local arg = select(i, ...)
        res[i] = L_impl(arg)
    end
    return L_impl(res)
end

L = LL_impl
```
