Two workers & worker termination (#198)

* Refactoring codecs

* Plugging in new processor

* Fixing decorator

* MozJPEG free issue

* Better worker aborting, and terminate workers that aren't used for 10 seconds

* Better comment

* Ooops, half-typed comment

* Uncommenting problematic line

* Surma fixed it!

* Abstracting WASM initialisation

* Better comment

* Don't need this.

* Adding ticket

* noInitalRun

* Reverting MozJPEG issue demo

* Making a const for worker timeout

* Inline docs

* Bail early rather than nesting

* Addressing nits

src/codecs/processor-worker.ts

@@ -0,0 +1,41 @@
+import { expose } from 'comlink';
+import { EncodeOptions as MozJPEGEncoderOptions } from './mozjpeg/encoder-meta';
+import { QuantizeOptions } from './imagequant/processor-meta';
+import { EncodeOptions as OptiPNGEncoderOptions } from './optipng/encoder-meta';
+import { EncodeOptions as WebPEncoderOptions } from './webp/encoder-meta';
+
+async function mozjpegEncode(
+  data: ImageData, options: MozJPEGEncoderOptions,
+): Promise<ArrayBuffer> {
+  const { encode } = await import('./mozjpeg/encoder');
+  return encode(data, options);
+}
+
+async function quantize(data: ImageData, opts: QuantizeOptions): Promise<ImageData> {
+  const { process } = await import('./imagequant/processor');
+  return process(data, opts);
+}
+
+async function optiPngEncode(
+  data: BufferSource, options: OptiPNGEncoderOptions,
+): Promise<ArrayBuffer> {
+  const { compress } = await import('./optipng/encoder');
+  return compress(data, options);
+}
+
+async function webpEncode(
+  data: ImageData, options: WebPEncoderOptions,
+): Promise<ArrayBuffer> {
+  const { encode } = await import('./webp/encoder');
+  return encode(data, options);
+}
+
+async function webpDecode(data: ArrayBuffer): Promise<ImageData> {
+  const { decode } = await import('./webp/decoder');
+  return decode(data);
+}
+
+const exports = { mozjpegEncode, quantize, optiPngEncode, webpEncode, webpDecode };
+export type ProcessorWorkerApi = typeof exports;
+
+expose(exports, self);