hide SSM fallback banner when not needed

Mute reported that, in 4:3 aspect ratio, the fallback banners were peeking out from behind the FadingBanner ActorProxy.

He provided some new zoom and positioning numbers that resolved that issue, but the zoom factor he provided (0.745) seemed to cause some strange artifact issues around the top edge of the FadingBanner ActorProxy...  Or, at least, it did on my Mac.

This led me to try a 0.75 zoom factor, which cleaned up the artifacts but causes about 2-3 pixels of the left side of the banner to be cut off.  Hmm.  I ... think this is probably preferable, but we'll see what people think.

I also added some code to just straight up hide the fallback banners when the current song or course has a banner.

hide all but primary Eval pane for Casual mode

don't limit each player to one screenshot on Eval

I had originally put the limit in place after observing too many novice players unwittingly saving screenshots to the MachineProfile, but things have changed since then.

Casual GameMode doesn't allow screenshots at all, and competitive players may very well want more than one screenshot of ScreenEvaluation now that there are multiple panes of information.

This commit also speeds up the ScreenShot animation.  4 seconds was too long; 1.5 feels better and is less likely to cause issues with a second screenshot being obscured by part of the first screenshot's animation(!).

handle negative StageTokens for not-EventMode

As the inline comment states:  This is somewhat hackish, but it serves to counteract Lua Hacks.

If ScreenGameplay was reloaded by a "gimmick" chart, then it is very possible that the Engine's concept of remaining stages will be incongruent with the Theme's.  Add stages back, Engine-side, if necessary.

This prevents us from returning to ScreenSelectMusic with negative stage tokens (engine-side) which manifests as an empty MusicWheel.

remove unnecessary check from MeasureCounter

Initial Public Release