speedup: load inquirer only when needed

around 80ms improve on my machine

$ avg_time 10 node ./bin/h1 --compbash --compgen _ _ "h1 "
real 0.444000
user 0.443000
sys 0.070000

$ avg_time 10 node ./bin/h1 --compbash --compgen _ _ "h1 "
real 0.367000
user 0.350000
sys 0.052000

Author: fredericosilva

lib/interactive.js

@@ -1,6 +1,5 @@
 'use strict';
 
-const inquirer = require('inquirer');
 const Cli = require('./cli');
 
 const verifyTTY= (fn) => (...args) => {
@@ -18,7 +17,7 @@ module.exports.prompt = verifyTTY((message, options = {}) => {
         validate: input => input.length === 0 ? 'Incorrect input' : true,
     }, options);
 
-    return inquirer.prompt(options);
+    return require('inquirer').prompt(options);
 });
 
 module.exports.select = verifyTTY((message, choices, options = {}) => {
@@ -30,7 +29,7 @@ module.exports.select = verifyTTY((message, choices, options = {}) => {
         validate: input => input.length === 0 ? 'Incorrect input' : true,
     }, options);
 
-    return inquirer.prompt(options);
+    return require('inquirer').prompt(options);
 });
 
 module.exports.confirm = verifyTTY((message, options = {}) => {
@@ -41,5 +40,5 @@ module.exports.confirm = verifyTTY((message, options = {}) => {
         default: false,
     }, options);
 
-    return inquirer.prompt(options);
+    return require('inquirer').prompt(options);
 });