Clarify pathname docs, follow spec with fragments (#2448)

* Clarify pathname docs, follow spec with fragments

- Valid URLs must not contain a `#` within its fragment.
  https://github.com/MithrilJS/mithril.js/issues/2445
- Our docs were a little confusing and misleading - `m.pathname` isn't
  aware of URLs, just path names.
- Removed the relevant extension to `m.parseQueryString` required to
  support the hash parsing extension. Now we just shave it off and
  ignore it.
- Fix support for arbitrary prefixes, so prefixes like `?#` are
  handled correctly.
- Add a bunch of tests to cover various areas of confusion and unusual
  edge cases.

* Update with PR [skip ci]

request/tests/test-request.js

@@ -73,6 +73,17 @@ o.spec("request", function() {
 				o(data).deepEquals({a: 1})
 			}).then(done)
 		})
+		o("first argument keeps protocol", function(done) {
+			mock.$defineRoutes({
+				"POST /item": function(request) {
+					o(request.rawUrl).equals("https://example.com/item")
+					return {status: 200, responseText: JSON.stringify({a: 1})}
+				}
+			})
+			request("https://example.com/item", {method: "POST"}).then(function(data) {
+				o(data).deepEquals({a: 1})
+			}).then(done)
+		})
 		o("works w/ parameterized data via GET", function(done) {
 			mock.$defineRoutes({
 				"GET /item": function(request) {