Before, if there was an error in the audio worker or in the disk
worker, the emulator would not start. This could happen, for example,
if the page is loaded directly from disk in Chrome instead of through
a server.
Now, even if there is an error, the emulator will start.
* Switch modules to `esnext` to allow `webpack` to see import statements
* Pass rom names into Apple2 class
* Move ROMs into `system` and `character` directories to allow webpack bundle appropriate ROMs.
* Wait for ROMs to load before completing initialization.
* Typescriptify all of the UI peripherals
This converts the audio, gamepad, keyboard, printer, and tape
peripherals into Typescript. This is a pretty mechanical change.
It does fix issue #72, though.
* Add and that were missing
