Rip screen drawing out of View

View handles communication and control of elements in the Layout.
Layout does the actual drawing.
Fix a long-standing regression for PageInfo

Because we were this struct as a value, the value inside Ctx never got updated :/
rip out page calculation
Rip out list area from layout
Make it possible to dynamically calculate y-offset for ListArea
Make UserPrompt calculate its veritical position dynamically
Change everything to use anchors via AnchorSettings
Make layout selectable from command line

Note: bottom-up is still broken
Fix the logic to check if a line is selected
Fix moving around with arrows
Allow setting layout from config file

...So you don't have to type it all the time!
Update README.md
Implement ScrollPageUp/ScrollPageDown

Based on comment at https://github.com/peco/peco/pull/172#issuecomment-52393224
Jesus, what am I, a CS 101 student?
Fix ToggleSelectionAndSelectNext

This action was doing the right thing, but the changes in the layout
was looking at the wrong line number
Use batch mode just in case
Fix README

As proposed by https://github.com/peco/peco/pull/172#commitcomment-7414889
Add notes to Changes file
Remove hardcoded height - 2 and use linesPerPage()
Merge pull request #172 from peco/selectable-layout

Selectable layout