Add Hi* helpers for hi-intensity colors

[rhysd]

Hi,

I added Hi*() helpers (like HiRed()) for hi-intensity colors as well as normal colors.

I added them because only 8 of 16 colors have helpers. I feel hi-intensity colors are as popular as normal colors and used in many places. At least, I wanted to use hi-black for making a text not stand out, and hi-white for making a text be noticeable.

[fatih]

Hi @rhysd This looks ok. I think it would be worth adding because it doesn't break anything. However I would like to see a small addition to the packages documentation that goes over this a little bit. Just check the other examples to get a sense.

[rhysd]

I fixed the point with rebasing.

[rhysd]

However I would like to see a small addition to the packages documentation that goes over this a little bit. Just check the other examples to get a sense.

I tried to revise docs instead of copy-and-paste docs of existing helpers in b4376ec. I'm not sure they are better documents than previous, tho.

[fatih]

@rhysd I meant the examples here: https://github.com/fatih/color/blob/master/doc.go

[rhysd]

@fatih ah, I see... I'll update it today :smile:

[rhysd]

I added Hi* helpers to example code in doc.

[fatih]

Thanks @rhysd, nice update 👍