Allow drag and drop of effects on items

[akrigline]

This change introduces drag and drop handlers for the Item Sheet to allow Effects to be dragged and dropped between items.

This also allows effects to be drag and dropped from an item onto an actor to emulate applying the effect.

Use Cases:

• Having configured a "Poisoned Dagger" with a "Poisioned" Effect, I would like to be able to quickly copy that effect to a "Poisioned Longsword".
  • Said items would not need to transfer their effect to their parent actor in order for the GM to use them on enemies.
• An item which replicates the effects of a spell that has active effects configured can quickly clone the effect of that spell.

Methodology

Copies what core does for dropping active effects on Actor Sheets, with one change:

• Sets the origin of the created effect to be the uuid of the new parent item.

Research

I've been doing this with with the module: Drop Effects on Items for several months and it's been very useful.

[Fyorl]

Good stuff, thanks. Just some code style suggestions from me.

[akrigline]

changes made @Fyorl thanks for the suggestions :)