Update dependencies and use esbuild for bundling

You may wonder why all these changes are done in one commit, and that's
because they're all kind of interrelated:
- I initially updated PureScript to 0.15.x, which produces code that
  uses ES modules instead of CommonJS ones
- The version of `purescript-decimals` in the 0.15.x package set was
  tested with decimal.js 10.3.1, so use that
- Since we're using ES modules now, I updated `clipboardy` and
  `xdg-basedir` to versions that use ES modules (I admit that I didn't
  have to do this one in this commit)
- `pulp browserify` doesn't work with PureScript 0.15.x, so I had to
  migrate to something else (I chose `esbuild`)

Side note: `purescript-parsing` 9.0.0 brings with it a wonderful
performance boost[1], which speeds up the test suite by 3 times on my
machine (from `102.231 s ± 0.485 s` to `34.666 s ± 0.299 s`).

[1]: purescript-contrib/purescript-parsing#154

Author: triallax

copy.js

@@ -1,6 +1,5 @@
-const { copyFileSync } = require("fs");
+import { copyFileSync } from "fs";
 
-copyFileSync("insect.js", "web/insect.js");
 copyFileSync("node_modules/keyboardevent-key-polyfill/index.js", "web/keyboardevent-key-polyfill.js");
 copyFileSync("node_modules/jquery/dist/jquery.min.js", "web/jquery.min.js");
 copyFileSync("node_modules/jquery.terminal/js/jquery.terminal.min.js", "web/jquery.terminal.min.js");

index.js

@@ -1,8 +1,7 @@
 #!/usr/bin/env node
 
-var os = require("os");
-var path = require("path");
-var Insect = require('./output/Insect/index.js');
+import * as Insect from "./output/Insect/index.js";
+import * as path from "path";
 
 var insectEnv = Insect.initialEnvironment;
 
@@ -46,7 +45,8 @@ if (process.argv.length >= 4) {
 }
 
 if (process.env.INSECT_NO_RC !== "true") {
-  var lineReader = require("line-reader");
+  var [os, lineReader] = await Promise.all([import("os"), import("line-reader")]);
+
   var rcFile = path.join(os.homedir(), ".insectrc");
   lineReader.eachLine(rcFile, function (line) {
     var res = runInsect(Insect.fmtPlain, line);
@@ -67,18 +67,14 @@ if (process.env.INSECT_NO_RC !== "true") {
   startInsect();
 }
 
-function startInsect() {
+async function startInsect() {
   var interactive = process.stdin.isTTY;
 
   if (interactive) {
-    var readline = require('readline');
-    var xdgBasedir = require('xdg-basedir');
-    var path = require('path');
-    var clipboardy = require('clipboardy');
-    var fs = require('fs');
+    var [fs, clipboardy, readline, xdgBasedir] = await Promise.all([import("fs"), import("clipboardy"), import("readline"), import("xdg-basedir")]);
 
     // Open the history file for reading and appending.
-    var historyFd = fs.openSync(path.join(xdgBasedir.data, "insect-history"), 'a+');
+    var historyFd = fs.openSync(path.join(xdgBasedir.xdgData, "insect-history"), 'a+');
 
     var maxHistoryLength = 5000;
 
@@ -161,11 +157,11 @@ function startInsect() {
 
     rl.prompt();
   } else {
-    // Read from non-interactive stream (shell pipe)
-
     if (typeof lineReader === "undefined") {
-      var lineReader = require("line-reader");
+      var lineReader = await import("line-reader");
     }
+
+    // Read from non-interactive stream (shell pipe)
     lineReader.eachLine(process.stdin, function(line) {
       var res = runInsect(Insect.fmtPlain, line);
       if (res) {