Minimize PyThaiNLP Dependencies

[BLKSerene]

Hi, thanks for the awesome project which I've used in mine.

But the tinydb dependency is only used in \corpus\core.py and corpus\__init__.py, so is it possible to remove this small dependency? (The reduction in the number of small dependencies helps me to package my program.)

[wannaphong]

Hello. I think there is no need to remove tinydb because tinydb is small size and it write in pure Python.