Improve tests: Add pretty_org fixtures to allow testing pretty printing

Until now we expected the .org file to print back to itself - we can't do that
when the input is not pretty printed already - with the introduction of blocks
with unindented content that will be the case.

org/html_test.go

@@ -7,14 +7,14 @@ import (
 
 func TestHTMLWriter(t *testing.T) {
 	for _, path := range orgTestFiles() {
+		expected := fileString(path[:len(path)-len(".org")] + ".html")
 		reader, writer := strings.NewReader(fileString(path)), NewHTMLWriter()
 		actual, err := NewDocument().SetPath(path).Parse(reader).Write(writer)
 		if err != nil {
 			t.Errorf("%s\n got error: %s", path, err)
 			continue
 		}
-		expected := fileString(path[:len(path)-len(".org")] + ".html")
-		if expected != actual {
+		if actual != expected {
 			t.Errorf("%s:\n%s'", path, diff(actual, expected))
 		} else {
 			t.Logf("%s: passed!", path)