Enable soft livereload of CSS and images

Prior to this commit a dummy JavaScript filename was sent to LiveReload when changing a static file (CSS, image etc.), forcing a full browser reload of the page.

This commit fixes this by sending the relative file path of the changed static resource, enabling partial live reloading for CSS- and image-changes. If more than one static file happens to end up in the same changeevent-batch, it will fall back to do a full refresh. To enable this logic, the change events with names ending with ".goutputstream*" is now filtered out as temporary.

Changes in dynamic content behaves like before.

Issue #490

helpers/helpers_test.go

@@ -122,3 +122,26 @@ func TestMakePermalink(t *testing.T) {
 		}
 	}
 }
+
+func TestMakePathRelative(t *testing.T) {
+	type test struct {
+		inPath, path1, path2, output string
+	}
+
+	data := []test{
+		{"/abc/bcd/ab.css", "/abc/bcd", "/bbc/bcd", "/ab.css"},
+		{"/abc/bcd/ab.css", "/abcd/bcd", "/abc/bcd", "/ab.css"},
+	}
+
+	for i, d := range data {
+		output, _ := MakePathRelative(d.inPath, d.path1, d.path2)
+		if d.output != output {
+			t.Errorf("Test #%d failed. Expected %q got %q", i, d.output, output)
+		}
+	}
+	_, error := MakePathRelative("a/b/c.ss", "/a/c", "/d/c", "/e/f")
+
+	if error == nil {
+		t.Errorf("Test #%d failed. Expected error")
+	}
+}