Upgrade libvips dependency to v8.5.4, plus other bumps

lib/input.js

@@ -1,6 +1,5 @@
 'use strict';
 
-const util = require('util');
 const color = require('color');
 const is = require('./is');
 const sharp = require('../build/Release/sharp.node');
@@ -143,7 +142,7 @@ function clone () {
   const that = this;
   // Clone existing options
   const clone = this.constructor.call();
-  util._extend(clone.options, this.options);
+  clone.options = Object.assign({}, this.options);
   // Pass 'finish' event to clone for Stream-based input
   this.on('finish', function () {
     // Clone inherits input data

package.json

@@ -68,26 +68,26 @@
     "caw": "^2.0.0",
     "color": "^1.0.3",
     "got": "^6.7.1",
-    "nan": "^2.5.1",
+    "nan": "^2.6.2",
     "semver": "^5.3.0",
     "tar": "^2.2.1"
   },
   "devDependencies": {
     "async": "^2.3.0",
     "bufferutil": "^3.0.0",
     "cc": "^1.0.0",
-    "documentation": "^4.0.0-beta.18",
+    "documentation": "^4.0.0-rc.0",
     "exif-reader": "^1.0.2",
     "icc": "^1.0.0",
-    "mocha": "^3.2.0",
-    "nyc": "^10.2.0",
+    "mocha": "^3.3.0",
+    "nyc": "^10.2.2",
     "rimraf": "^2.5.4",
-    "semistandard": "^10.0.0",
+    "semistandard": "^11.0.0",
     "unzip": "^0.1.11"
   },
   "license": "Apache-2.0",
   "config": {
-    "libvips": "8.5.1"
+    "libvips": "8.5.4"
   },
   "engines": {
     "node": ">=4"

test/unit/io.js

@@ -288,7 +288,7 @@ describe('Input/output', function () {
   });
 
   it('Fail when input is empty Buffer', function (done) {
-    sharp(new Buffer(0)).toBuffer().then(function () {
+    sharp(Buffer.alloc(0)).toBuffer().then(function () {
       assert(false);
       done();
     }).catch(function (err) {
@@ -298,7 +298,7 @@ describe('Input/output', function () {
   });
 
   it('Fail when input is invalid Buffer', function (done) {
-    sharp(new Buffer([0x1, 0x2, 0x3, 0x4])).toBuffer().then(function () {
+    sharp(Buffer.from([0x1, 0x2, 0x3, 0x4])).toBuffer().then(function () {
       assert(false);
       done();
     }).catch(function (err) {