refactor: move DeepLX to DeepL

style: API Key uppercase

refactor: move AddPage to uiInit

docs: play sound -> playing text to speech

docs: add go build

docs: show ArgosTranslate as default translator

refactor: make Language, TTSLock and EngineName to struct in Translator

GetSrcLang, GetDstLang, SetSrcLang, SetDstLang, SwapLang are reusable
functions from translator to translator. So make Language struct.

GetEngineName is also a reusable function. So make EngineName struct.

Finally, let Translator to inherit those functions in these three
(Language, TTSLock, EngineName) structs. No need to write the duplicated
functions for each Translator.

feat(translator): add ApertiumTranslate (#13)

refactor: replace AddItem with attachItems

attachItems implements adding multi items & centering items

chore: not use `--remove-files` option in tar

It cause some problem in macos