Database Context issues when Items change their owner

[sven-n]

Currently it's not taken care of Items which are changing their owner. This can happen by several ways:

• Item dropped
  • Item will disappear after some time -> Item will be saved by dropping player context
  • Item will be picked up by another player -> Exception at next save point
• Item is traded -> Exception at next save point

[sven-n]

The item drop issue is still open.

Also at trade, when saving the persistence context of the receiving player, the item is inserted instead of updated.

[sven-n]

Should be fixed by now (commit f16a15d), forgot to reference the issue in the commit message.