Fix #399 (fussy popover target)

Some shuffling of task popover functionality to address the difficulty of targeting the "notes" speech bubble icon.

* The icon itself no longer has any popover. It simply cues the user that more detail is available.
* Popovers now appear when you mouse over the task text. For equipment Rewards, mousing over the shop sprite also works.
* Implemented and tested for tasks, static rewards, spells, and Winter special spells.
* Tested with drag-drop sort operations. Looks a little funky, but works fine.