mvmOS 0.37.0-beta: one shell for every game window

Every game in mvmOS is played on its own public page in Game Hub, and until now each game had to build the desktop window that sends you there. This release puts that window in the system itself. A game app now says what it is called and what it looks like, and the shared launcher does the rest: the title, the one line about what the game is, the button that opens it full screen in its own tab, and the space for whatever belongs to the person who runs the server rather than to a player. That split is deliberate. A game is played where the accounts, the scores and the invitations are, which is the public Game Hub page — that is the only place anyone other than the single session logged into this desktop can play at all, and on a phone it is the only place a game gets the whole screen. The desktop window is what the owner of the installation sees: settings today, and whatever a game needs to be configured with tomorrow. Game Hub is now treated as the requirement it always was. A game window opened on an installation without it no longer shows a Play button that leads nowhere. It says plainly what is missing and offers to install Game Hub on the spot, asking first about the server component that comes with it, and it checks again on every render — so the moment the install finishes, the same button turns into Play. Two games that use this launcher, Stonehold and Tower Defense, are released in the Store today and need this version.