loadUrl enhancements (#134)

`loadUrl` enhancements

- Make `options` parameter optional
- Allow partial overriding of instance options when calling `loadUrl` directly
- Make `requestOptions` optional
- Document `loadUrl` usage and provide examples

tests/lib/proto/parse-options.js

@@ -1,49 +0,0 @@
-var tape = require("tape")
-
-var parseOptions = require("../../../lib/proto/parse-options.js")
-tape("test parse initalization options function", function(t) {
-  t.test("- default options", function(t) {
-    var pjax = {}
-    parseOptions.call(pjax, {})
-
-    t.equal(pjax.options.elements, "a[href], form[action]")
-    t.equal(pjax.options.selectors.length, 2, "selectors length")
-    t.equal(pjax.options.selectors[0], "title")
-    t.equal(pjax.options.selectors[1], ".js-Pjax")
-
-    t.equal(typeof pjax.options.switches, "object")
-    t.equal(Object.keys(pjax.options.switches).length, 2)// head and body
-
-    t.equal(typeof pjax.options.switchesOptions, "object")
-    t.equal(Object.keys(pjax.options.switchesOptions).length, 0)
-
-    t.equal(pjax.options.history, true)
-    t.equal(typeof pjax.options.analytics, "function")
-    t.equal(pjax.options.scrollTo, 0)
-    t.equal(pjax.options.scrollRestoration, true)
-    t.equal(pjax.options.cacheBust, true)
-    t.equal(pjax.options.debug, false)
-    t.equal(pjax.options.currentUrlFullReload, false)
-    t.end()
-  })
-
-  // verify analytics always ends up as a function even when passed not a function
-  t.test("- analytics is a function", function(t) {
-    var pjax = {}
-    parseOptions.call(pjax, {analytics: "some string"})
-
-    t.deepEqual(typeof pjax.options.analytics, "function")
-    t.end()
-  })
-
-  // verify that the value false for scrollTo is not squashed
-  t.test("- scrollTo remains false", function(t) {
-    var pjax = {}
-    parseOptions.call(pjax, {scrollTo: false})
-
-    t.deepEqual(pjax.options.scrollTo, false)
-    t.end()
-  })
-
-  t.end()
-})