added(*): Implmented And and Or operations using uint256 package

[0xsimulacra]

The current pull request implement "And" and "Or" operations using only "uint256" package and not replaying on "math.big".

The test passed for me and it seems correct. Howerever I might be wrong :)

Just a side note, even on the "math.big" package there this logical expression:

 // x | (-y) == x | ^(y-1) == ^((y-1) &^ x) == -(^((y-1) &^ x) + 1)

However the least part (that is " -(^((y-1) &^ x) + 1)"), I suspect that is wrong, the correct should be, from my understanding, '"-(((y-1) &^ x) + 1)" i.e without the "not" operator in the begining. What make me also believe that it is only a typo is that this corrected expresion without the "not" operator in the begining is exactly what is implmented in "math.big" package.

Anyways, I followed closely what is implemented in "math.big" in my pull request.

[linhbkhn95]

Hi @0xsimulacra
Thank your PR.
I have known this problem. So, I marked it as TODO work. But, I don't have time to do it from that time.
LGTM!

[0xsimulacra]

Hi @linhbkhn95,

The pleasure is mine and thank you for your input.

Yes, I have seen the TODO marking inside the conserned functions when I've read them the first time, hence I wanted to work on them.