Stats and effects update V0_5_0

Changes

• Improved how current stats are displayed
• Improved relative item descriptions.
• Added chain lightning effect

• Changed health downgrades to not take health unless at full health.
• Made attack delay modifiers relative to current value.
• Added health regeneration.
• Added an XP gain stat.
• Added explosion effects.
• Added several new items.

Fixes

• Fixed current stat display staying on screen when an item is selected while hovering over the stat name.
• Fixed current stat display not closing when moving the mouse out of the top of the text box.