MBS-2411, force https:// on the login screen.
MBS-2411, use c->req->secure instead of "manually" looking at HTTP_X_FORWARDED_PROTO.
MBS-2411, handle redirects to/from https in Controller::Root.  Redirect to SSL on /register.
MBS-2411, forgot to include a return after the redirect in the previous commit.
MBS-2411, remove unused $secure variable from Controller::User.
MBS-5687, Detect and notify the user when a race condition occurs with two editors editing the same tracklist.
MBS-2411, changes based on feedback from code review.

- Rename REQUIRE_SSL_ENABLED to SSL_REDIRECTS_ENABLED
- Remove remnants of old ?secure=1 implementation of returning to http://
- Use Hook::LexWrap in tests to set SSL_REDIRECTS_ENABLED.
Merge branch 'mbs-5687' into beta

* mbs-5687:
  MBS-5687, Detect and notify the user when a race condition occurs with two editors editing the same tracklist.
Merge branch 'mbs-2411' into beta

* mbs-2411:
  MBS-2411, changes based on feedback from code review.
  MBS-2411, remove unused $secure variable from Controller::User.
  MBS-2411, forgot to include a return after the redirect in the previous commit.
  MBS-2411, handle redirects to/from https in Controller::Root.  Redirect to SSL on /register.
  MBS-2411, use c->req->secure instead of "manually" looking at HTTP_X_FORWARDED_PROTO.
  MBS-2411, force https:// on the login screen.