feat: config and approximate equality (#19)

Establishes a global config object for a TypeDispatcher instance, so far
  with just properties representing comparison tolerances. Begins a
  "relational" group of functions with basic approximate equality, and
  an initial primitive ordering comparison. Ensures that methods that
  depend on properties of `config` will be properly updated when those
  properties change.

Reviewed-on: #19
Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Co-committed-by: Glen Whitney <glen@studioinfinity.org>

src/generic/__test__/utils.spec.js

@@ -0,0 +1,13 @@
+import assert from 'assert'
+import math from '#nanomath'
+
+describe('generic utility functions', () => {
+   it('tests whether an element is zero', () => {
+      const {isZero} = math
+      assert(!isZero(3))
+      assert(isZero(3e-16))
+      assert(isZero(false))
+      assert(!isZero(true))
+      assert(isZero(undefined))
+   })
+})