refactor: switch to bignumber.js (#927)

BREAKING CHANGE: All API methods that returned [`big.js`](https://github.com/MikeMcl/big.js/) instances now return [`bignumber.js`](https://github.com/MikeMcl/bignumber.js/) instances.

License: MIT
Signed-off-by: Alan Shaw <alan.shaw@protocol.ai>

Author: Alan Shaw

Diff for: package.json

@@ -28,7 +28,7 @@
   },
   "dependencies": {
     "async": "^2.6.1",
-    "big.js": "^5.2.2",
+    "bignumber.js": "^8.0.2",
     "bl": "^2.1.2",
     "bs58": "^4.0.1",
     "cids": "~0.5.5",

Diff for: src/bitswap/stat.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const promisify = require('promisify-es6')
-const Big = require('big.js')
+const Big = require('bignumber.js')
 
 const transform = function (res, callback) {
   callback(null, {

Diff for: src/repo/stat.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const promisify = require('promisify-es6')
-const Big = require('big.js')
+const Big = require('bignumber.js')
 
 const transform = function (res, callback) {
   callback(null, {

Diff for: src/stats/bitswap.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const promisify = require('promisify-es6')
-const Big = require('big.js')
+const Big = require('bignumber.js')
 
 const transform = function (res, callback) {
   callback(null, {

Diff for: src/stats/bw-util.js

@@ -1,6 +1,6 @@
 'use strict'
 
-const Big = require('big.js')
+const Big = require('bignumber.js')
 
 module.exports = (chunk) => {
   return {

Diff for: src/stats/repo.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const promisify = require('promisify-es6')
-const Big = require('big.js')
+const Big = require('bignumber.js')
 
 const transform = function (res, callback) {
   callback(null, {