Nopo

- Add select methods and switch in method;
- Fix typos

Add force mode for clear:

python
el.clear(force=False) Clear the element. Use force=True to ensure the element can be cleared to deal with some situation.
el.send_keys(keys, clear=False, force_clear=False) Send keys to element. If clear is True, clear the element before sending. If clear and force are True, clear will be in force mode.
el.csk(keys, force_clear=False) Clear and send keys to element. If force_clear is True, clear will be in force mode.
el.nn_csk(keys, force_clear=False) Clear and send keys if keys is not None. If force_clear is True, clear will be in force mode.

- optimize `__len__` and `__getitem__` of `Els`
- modify CRLF to LF

Optimize els.

Notice: nopo is still in development, so the API is currently unstable.

Fix some typos.

The first release.

Notice: nopo is still in development, so the API is currently unstable.