feat: TypeScript typings for Dispatcher implementations

A first pass at specifying some implementations in TypeScript
  that actually compiles. It doesn't do anything, as installing
  types and operation specifications are currently dummy operations,
  but they are all invoked.

src/numbers/type.ts

@@ -0,0 +1,13 @@
+export const number_type = {
+   before: ['Complex'],
+   test: (n: unknown): n is number => typeof n === 'number',
+   from: {string: s => +s}
+}
+
+export const zero = (a: number) => 0
+
+declare module "../core/Dispatcher" {
+   interface ImplementationTypes {
+      zero_numbers: typeof zero
+   }
+}