[READY][CR] Container Inventory Management - Liquids

As discussed in #9524 I added functionality into AIM to allow for transfer of liquids between containers.

You select one container as target and then 'move' other containers into it from other pane. Unloading is automatic.

Screenshots:
![cim01](https://cloud.githubusercontent.com/assets/6969268/4749034/0a646dba-5a7e-11e4-85c1-f1d949481c05.PNG)

![cim02](https://cloud.githubusercontent.com/assets/6969268/4749038/0f40d6d4-5a7e-11e4-9088-66cc90218cbc.PNG)

![cim03](https://cloud.githubusercontent.com/assets/6969268/4749040/12244a66-5a7e-11e4-825b-82d6ba7b5be4.PNG)

Issues:
- [X] CATEGORY_SELECTION set to 't'
- [X] selected container is persisted in uistate as location, index, type and content type
- [X] refactor common part of code from move_content and game::handle_liquid