Add 'censor middle only' feature

[emso-c]

Firstly, thanks for the amazing module!

I've added a censor middle only feature which censors only the middle of the texts.

Can only be used if middle_only argument is set to True and it's set to False by default, so it doesn't break anything or alter the way the module works.

I didn't really test edge cases that much but it passes all 30 unit tests.

Without middle_only parameter (same result with middle_only=False):

from better_profanity import profanity

if __name__ == "__main__":
    profanity.load_censor_words()

    text = "fucking shit"
    print(profanity.censor(text))
    # "**** ****"

With middle_only parameter:

from better_profanity import profanity

if __name__ == "__main__":
    profanity.load_censor_words()

    text = "fucking shit"
    print(profanity.censor(text, middle_only=True))
    # "f*****g s**t"

Also added env/ to gitignore since I was using a virtual environment, discard it if you want.

[snguyenthanh]

May I ask what the use case for "middle only" censoring is ? Or is it just a personal preference ?

[emso-c]

Actually we just needed a way to determine the true length of the censored text. With the current method it returns 4 regardless of the words length. Not censoring the initial and the last letter was a personal preference in order to make the word more "guessable".

[snguyenthanh]

Hmm I see. I think that would be fine, to give the users more options.

By the way, as #36 already includes the feature in the PR, I think we could close this one ?

[emso-c]

Oh sure, sorry about that.

Closing rn.