Update README.md
Update README.md
Refactor NewCtx so that it receives the options struct

see
https://github.com/peco/peco/commit/9660496d99d37184997ccf75e1be831b7d1c70f5#commitcomment-6857198
Merge pull request #122 from peco/refactor-ctx-constructor

Refactor NewCtx so that it receives the options struct
Refactor keymap

Created Action/ActionFunc to wrap common operations
refs #121
Add SelectNone action

which clears current selection. Also make C-g the default key binding
for this.
Add SelectVisible action

which selects every match that is currently displayed on screen. To
determine which matches are currently visible I chose to expose
currentPage (index, offset, and page size) through the Context. This is
updated every time the screen is redrawn.
Add SelectAll action

which selects every match, visible or not.