Update dev deps, deconstify all the functions, API doc refresh

package.json

@@ -72,17 +72,17 @@
     "tar": "^2.2.1"
   },
   "devDependencies": {
-    "async": "^2.1.4",
+    "async": "^2.2.0",
     "bufferutil": "^3.0.0",
     "cc": "^1.0.0",
-    "cross-env": "^3.2.3",
+    "cross-env": "^4.0.0",
     "documentation": "^4.0.0-beta.18",
     "exif-reader": "^1.0.2",
     "icc": "^1.0.0",
     "mocha": "^3.2.0",
-    "nyc": "^10.1.2",
+    "nyc": "^10.2.0",
     "rimraf": "^2.5.4",
-    "semistandard": "^9.2.1",
+    "semistandard": "^10.0.0",
     "unzip": "^0.1.11"
   },
   "license": "Apache-2.0",