Major Feature Update

-Added new mode : Player vs Computer
-Now there are 2 modes namely Player vs Computer and Player vs Player
-Default mode is Player vs Computer
-Added option to change the mode
-In PvC mode user always inputs X and the computer inputs O
-Added different result messages based on the mode
-Added more comments

First Release

-Input X and O alternatively by clicking on the buttons in the grid
-First to start is always X
-Shows you who won or if it's a draw
-Restart Game Option
-About option with version, link for releases and for sources
-PEP 8 format
-Object Oriented
-Comments to easily understand code