Added a bitmap cache to reduce disk access and memory usage.
Refactoring.
Create item popups on first use rather than on initial load.
This gives a massive performance improvment when switching between tabs
and characters.
Do not call InitializeComponent() in the ItemDisplay constructor, instead
create the grid manually.
This removes a call to Application.LoadComponent for each and every item
load wich reduces the initial load time slightly.
Show item hover image on empty sockets.
Refactoring.
Removed duplicate call.
Reuse the item hover control. This makes the hover function snappier and
reduces the overall memory usage of the program after long sessions.
Fixed not beeing able to see the item hover between gems.
Merge pull request #3 from BlueManiac/master

Item loading performance improvements, memory usage reduction and some small fixes.