Inventory-manipulation Framework

To ensure compatibility through mods (specifically inventory-manipulators and IInventory-implementations), Forge should provide a standardized model of inventory manipulation. 

Inventory-manipulators can now rely on this framework to do the heavy lifting, and they just get what they need. 

In addition to that, this framework introduces the concepts of: 
 * Dynamic Inventory: an implementation that can decide what types/amounts of items can go in/out.
 * Custom Inventory: an inventory that (for whatever reason) needs to handle it's own inventory. 

For more information, please read the forum post: http://www.minecraftforge.net/forum/index.php/topic,6321.0.html

I'm open to feedback. If there is a need for clarification, I'll be happy to discuss this matter.