Emscripten: Solution for savegame collisions

[Ghabry]

Same solution as proposed in https://community.easyrpg.org/t/browser-version-saves-not-being-kept-when-leaving-and-returning-to-game-page/927 just a bit cleaner.

Usage (before the shell js file)

<script>
Module = {
  EASYRPG_GAME = "UniqueGameId"
};
</script>

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Btw atsumaru loads the shell file and an "override script" with script defer. Defer is nice because it enforces an execution order. Normal emscripten generator uses async so we cannot use this behaviour. :(

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Also I got errors now because of missing dynCall. Maybe SDL update.

[Ghabry]

Jenkins: test this please

[Ghabry]

server path would be obviously the easiest solution but this would break the saves for our own hosted web player (all versions share the same savegames, sometimes useful).

Will think about this again. Converting to a draft...

[Ghabry]

This is possible now through the game arg in the easyrpg module