Add ctrl-w: delete previous word
Merge pull request #18 from gsserge/master

Yet Another Ctrl+W
Refactoring: editing state is now a structure.
All functions commented.
README updated (we know have completion).
linenosePrompt() -> linenoiseEdit().
Refactoring: code split into sections. Chars insertion as a function.
More stuff on .gitignore
Refactoring WIP #1: split in functions.
Off-by-one overflow fixed. Was a silent bug before refactoring.
Delete and ctrl-d refactored into linenoiseEditDelete()
Backspace functionality refactored into linenoiseEditBackspace() function.
Clarified with ctrl-t does in comments.
Ctrl-w refactored into linenoiseEditDeletePrevWord().
Escapes dispatching better documented.
Merge branch 'master' of github.com:marcomorain/linenoise