add TranslationReg methods transform for instance of LuaTranslation

[shewer]

增加 transltion 轉換 語法糖
Translation( func, tran,...) == tran:tranform(func,...)

Translation(func1, Translation(func2,tran) )
等同於 tran:transform(func2):transform(func1)
ex:

local function select_quality(tarn, quality)
       for cand in tran:iter() do 
            if cand.quality > 1.5 then
                yield(cand)
             end
        end
 end

filter.func(inp,env,cands)  -- inp  : instance of Translation
  local tran = inp:transform( select_quality, 1.5)
  for cand in tran:iter() do 
           yield(cand)
    end
end