Modularise JS source in 'lib' subdirectory.

Generate public API documention via jsdoc comments.

package.json

@@ -34,9 +34,10 @@
     "clean": "rm -rf node_modules/ build/ vendor/ coverage/ test/fixtures/output.*",
     "test": "semistandard && cross-env VIPS_WARNING=0 nyc --reporter=lcov --branches=96 mocha --slow=5000 --timeout=60000 ./test/unit/*.js",
     "test-leak": "./test/leak/leak.sh",
-    "test-packaging": "./packaging/test-linux-x64.sh"
+    "test-packaging": "./packaging/test-linux-x64.sh",
+    "docs": "for m in constructor input resize composite operation colour channel output utility; do documentation build --shallow --format=md lib/$m.js >docs/api-$m.md; done"
   },
-  "main": "index.js",
+  "main": "lib/",
   "repository": {
     "type": "git",
     "url": "git://github.com/lovell/sharp"
@@ -59,7 +60,7 @@
   "dependencies": {
     "caw": "^2.0.0",
     "color": "^0.11.3",
-    "got": "^6.5.0",
+    "got": "^6.6.0",
     "nan": "^2.4.0",
     "semver": "^5.3.0",
     "tar": "^2.2.1"
@@ -68,6 +69,7 @@
     "async": "^2.1.2",
     "bufferutil": "^1.2.1",
     "cross-env": "^3.1.3",
+    "documentation": "^4.0.0-beta11",
     "exif-reader": "^1.0.1",
     "icc": "^0.0.2",
     "mocha": "^3.1.2",