insufficient use of vegas in game

[pixelzoom]

Related to #99

Area Model is not using common game components.

• Level-selection buttons are at GameAreaScreenView line 102. It should be using LevelSelectionItemNodeDeprecated, or the newer LevelSelectionButton which will soon be replacing LevelSelectionItemNodeDeprecated.

• Status bar is implemented in GameStatusBar. It should be using the well-established ScoreboardBar, which will need to be enhanced to show the score format used by Area Model.

• The score display is currently using ProgressIndicator, which is deprecated. It should be using ScoreDisplayDiscreetStars.

[pixelzoom]

Beside the fact that game design should inform vegas, the other big reasons for using vegas components are a11y and phet-io. If you use common-code, you'll get these features for free when the common-code is instrumented. When you roll your own, you create more a11y and phet-io work.

[jonathanolson]

I'll presumably use the (planned) bar once it has the "Score: {stars}" option, the LevelSelectionButton (new one). I'll also add a dissolve (instead of a wipe back) when Start Over is pressed.

[jonathanolson]

Switched to LevelSelectionButton above.

[jonathanolson]

Completed switch with the above commits.