fix(Types): Move distinct types into distinct identifiers

This allows types to be collected; prior to this commit they
   were conflicting from different modules.

   Uses this fix to extend sqrt to bigint, with the convention
   that it is undefined for non-perfect squares when 'predictable'
   is false and is the "best" approximation to the square root when
   'predictable' is true. Furthermore, for negative bigints, you might
   get a Gaussian integer when predictable is false; or you will just get
   your argument back when 'predictable' is true because what other
   bigint could you give back for a negative bigint?

   Also had to modify tests on the sign in sqrt(Complex) and add functions
   'zero' and 'one' to get types to match, as expected in #27.

   Adds numerous tests.

   Resolves #26.
   Resolves #27.

test/bigint/_all.mjs

@@ -0,0 +1,55 @@
+import assert from 'assert'
+import math from '../../src/pocomath.mjs'
+import PocomathInstance from '../../src/core/PocomathInstance.mjs'
+import * as bigintSqrt from '../../src/bigint/sqrt.mjs'
+import * as complex from '../../src/complex/all.mjs'
+import * as bigints from '../../src/bigint/all.mjs'
+
+describe('bigint', () => {
+   it('can divide', () => {
+      assert.strictEqual(math.divide(15n, 5n), 3n)
+      assert.strictEqual(math.divide(14n, 5n), undefined)
+      math.config.predictable = true
+      assert.strictEqual(math.divide(14n, 5n), 2n)
+      assert.strictEqual(math.divide(-14n, 5n), -3n)
+      assert.strictEqual(math.divide(14n, -5n), -3n)
+      assert.strictEqual(math.divide(-14n, -5n), 2n)
+      math.config.predictable = false
+   })
+ 
+   it('supports sqrt', () => {
+      assert.strictEqual(math.sqrt(0n), 0n)
+      assert.strictEqual(math.sqrt(4n), 2n)
+      assert.strictEqual(math.sqrt(5n), undefined)
+      assert.strictEqual(
+         math.sqrt(82120471531550314555681345949499512621827274120673745141541602816614526075010755373654280259022317599142038423759320355177481886719814621305828811322920076213800348341464996337890625n),
+         9062034624274524065844376014975805577107171799890766992670739972241112960081909332275390625n)
+      assert.deepStrictEqual(math.sqrt(-9n), math.complex(0n, 3n))
+      assert.deepStrictEqual(
+         math.sqrt(math.complex(5n, 12n)),
+         math.complex(3n, 2n))
+      assert.deepStrictEqual(math.sqrt(math.complex(1n, 0n)), 1n)
+      assert.deepStrictEqual(math.sqrt(math.complex(0n, 1n)), undefined)
+      math.config.predictable = true
+      assert.strictEqual(math.sqrt(-9n), -9n)
+      assert.deepStrictEqual(
+         math.sqrt(math.complex(1n, 0n)), math.complex(1n, 0n))
+      assert.deepStrictEqual(
+         math.sqrt(math.complex(0n, 1n)), math.complex(0n, 0n))
+      assert.deepStrictEqual(
+         math.sqrt(math.complex(0n, 2n)), math.complex(1n, 1n))
+      math.config.predictable = false
+      assert.deepStrictEqual(math.sqrt(-1024n), math.complex(0n, 32n))
+   })
+
+   it('supports sqrt by itself', () => {
+      const bo = new PocomathInstance('BigInts Only')
+      bo.install(bigintSqrt)
+      assert.strictEqual(bo.sqrt(256n), 16n)
+      assert.strictEqual(bo.sqrt(-17n), undefined)
+      bo.install(complex)
+      bo.install(bigints)
+      assert.deepStrictEqual(bo.sqrt(-3249n), bo.complex(0n, 57n))
+   })
+
+})