Possible alternate form of quiver (based on stacks)

I am not sure abut this TBH, all of the old version of ther quiver is still in the source code (everything new has a "2" on the end). I wanted to give you the oportunity to aprove on the changes.

Basically rather than having a basic counter I have made the IArrowContainer stack based. There is also an extra tag for a "Selected Slot". You can add arrows like the old one (although only 1 stack at a time for now) but it should have the ability to accept other arrow types when we create them.

When a player has a bow equipped there will be a small gui at the top of the screen showing the 5 slots (I was playing with the number and accidentally left it at 5, recommend we change it to 4). The current slot will be highlighted. The gui is based off the default hotbar so should follow your texture pack. Pressing 'Z' will select the next arrow slot. The selected slot will be the arrow that is fired.

I will allow you to merge this one if you like the change

![2013-08-21_15 52 25](https://f.cloud.github.com/assets/3378906/999249/f9de53a6-0a25-11e3-817a-b17fbb3c2644.png)
![2013-08-21_15 52 20](https://f.cloud.github.com/assets/3378906/999250/fcffdf1e-0a25-11e3-858b-9d056d000c48.png)