Reader "Jumps"

[aef-]

This issue is to add the concept of "Jumps". If I click to go to an Appendix, and scroll, and then perhaps click to go to another Appendix or page, I want to be able to easily return to where I originally started.

• Interface for "Jumps" lives within Toolbar. Can use same design as Table of Contents.
• Clicking to go to a page will add the original page to the jump stack (Table of Contents header + Page #)
• Hotkeys for going up or down the stack.
• Stack limits to 10
• Hot key to pop-up a "Jump to page X"