Snapshotting and effect handling for external entities are not handled correctly

[Jofairden]

The current snapshotting for modifiers is mediocre and buggy at best.
A solution must be created for this problem

Scope:

• Projectiles
• NPCs
• Projectiles shot by friendlies (minions)

Proposal

Proposed design: a snapshot of current active modifiers must be given to a particular entity (projectile, npc etc.) which can then be used in the appropriate hooks for effects. This will likely turn into boilerplate like ModifierItem.cs

[Jofairden]

TBD: Refactor ModifierEffect to ModifierPlayerEffect, add ModifierProjectileEffect and ModifierNpcEffect as new one.