Allow picking up of own dropped block in claim

[copygirl]

When a carried block is dropped on damage or death within a claim, it should be possible for the owner to take back their possessions, instead of being prevented from doing so due to the claim.

• Save the "owner" somehow (by name?) when the block is forcibly dropped
• Ignore permission check if the same player attempts to pick up their own block again
• Do not change any other behavior: Other players can still interact with, pick up, destroy a dropped block (as long as they have permission to do so within a claim)
• Intentionally placing carrying blocks does not save the "owner" property - and shouldn't be a problem as you aren't allowed to place them in claims anyway

[copygirl]

Update: Considering that on death, items would be dropped for any player to pick up, I think it would be important for any player to be able to pick up the dropped block as well.

This prevents an exploit where a player could intentionally drop a block in a protected area (such as a Trader's, or a server's protected spawn) without others having the ability to clean it up, potentially blocking pathways.

Unfortunately, I can't at the moment think of a way to show to players the difference between a regular block and one that could be picked up despite of the permission restrictions. There is also an issue where dropped blocks could potentially mess with blocks that are replaceable (water, grass, certain plants), so this should be considered as well.