This should be made available in emscripten in a decent way.
Possibly after unmount, to free the database lock and allow performing
operations on it from javascript after the Emscripten Runtime has
exited.
The engine now expects to emscripten FS to be setup and sync-ed before
main is called. This is exposed via `Module["initFS"]` which also allows
to setup multiple persistence paths (internal use only for now).
Additionally, FS syncing is done **once** for every loop if at least one
file in a persistent path was open for writing and closed, and if the FS
is not syncing already.
This should potentially fix issues reported by users where "autosave"
would not work on the web (never calling `syncfs` because of too many
writes).
Add missing semicolumns in engine.js
Add optional extra args to JS Engine.startGame
Remove loader.js, explicit noExitRuntime.
Also add onExit callback (undocumented in emscripten)
- Refactored the Engine code, splitted across files.
- Use MODULARIZE option to build emscripten code into it's own closure.
- Enable lto support (saves ~2MiB in release).
- Enable optional closure compiler pass for JS and generated code.
- Enable optional pthreads support.
- Can now build with tools=yes (not much to see yet).
- Dropped some deprecated code for older toolchains.
