Added a new weapon: the railgun.

Its ment to help you on waves where there are many more enemies since the railgun one shots all of them except for the boss zombie.

Alongside this, I also added the ability to swap between your pistol and your main weapon using the 1 and 2 key but keep in mind that you can only swap between weapons when you have a gun other than the pistol. Ultimately, this was implemented to make the game easier since many players have noted that the game was a little difficult.

Finally, I also added a melee function in which pressing F pushes back the zombie you are attacking as long as you are close to it. This was created as a way to attack while reloading though it does cancel your reload. Also in a one on one situation you can combo the zombie with this function.