Import bundled Insect in index.js

Fixes sharkdp#310, and provides a start for sharkdp#306.

This improves the startup time on my machine significantly. I'll let the
benchmark results speak for themselves:

Before commit:

| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|:---|---:|---:|---:|---:|
| `Startup time (insect '1+1')` | 513.9 ± 24.4 | 496.4 | 581.2 | 1.00 |

| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|:---|---:|---:|---:|---:|
| `Startup time, stdin mode (insect < computations-1.ins)` | 535.5 ± 14.2 | 524.6 | 572.7 | 1.00 |

| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|:---|---:|---:|---:|---:|
| `Evaluation speed (insect < computations-160.ins)` | 1502.1 ± 42.4 | 1466.2 | 1580.7 | 1.00 |

After commit:

| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|:---|---:|---:|---:|---:|
| `Startup time (insect '1+1')` | 192.4 ± 18.5 | 185.4 | 259.1 | 1.00 |

| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|:---|---:|---:|---:|---:|
| `Startup time, stdin mode (insect < computations-1.ins)` | 208.1 ± 2.0 | 204.8 | 212.2 | 1.00 |

| Command | Mean [ms] | Min [ms] | Max [ms] | Relative |
|:---|---:|---:|---:|---:|
| `Evaluation speed (insect < computations-160.ins)` | 1153.0 ± 17.6 | 1136.6 | 1198.3 | 1.00 |

Also, this commit causes `output` to not be published to NPM, which
makes for a much smaller installation size: Insect 5.7.0 on NPM has an
unpacked size of 29.2 MBs, but `npm publish --dry-run` with this commit
reports 378.8 kB. `.npmignore` was also removed, as the `files` property
in `package.json` includes only the files we want, so `.npmignore` does
basically nothing. Read
https://docs.npmjs.com/cli/v8/configuring-npm/package-json/#files for
more information.

This commit additionally makes a small modification to `index.js` to
make it work with Node 12. Unfortunately, at least one of our
dependencies (`clipboardy`) does not support Node 10, so I could not
make `index.js` work with Node 10.

.gitignore

@@ -3,6 +3,7 @@
 /.spago/
 /.psc*
 /.psa*
+/insect.js
 /docs/insect.1
 /web/*.js
 /web/terminal.css

index.js

@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 
-import * as Insect from "./output/Insect/index.js";
+import * as Insect from "./insect.js";
 import * as path from "path";
 
 var insectEnv = Insect.initialEnvironment;
@@ -45,24 +45,27 @@ if (process.argv.length >= 4) {
 }
 
 if (process.env.INSECT_NO_RC !== "true") {
-  var [os, lineReader] = await Promise.all([import("os"), import("line-reader")]);
+  // Node 12 does not support top-level await.
+  (async function() {
+    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);
-    // We really only care when it breaks
-    if (res && res.msgType === "error") {
-      console.error(res.msg);
-      process.exit(1);
-    }
-  }, function (err) {
-    // If the file doesn't exist, that's fine
-    if (err && err.code !== "ENOENT") {
-      throw err;
-    } else {
-      startInsect();
-    }
-  });
+    var rcFile = path.join(os.homedir(), ".insectrc");
+    lineReader.eachLine(rcFile, function (line) {
+      var res = runInsect(Insect.fmtPlain, line);
+      // We really only care when it breaks
+      if (res && res.msgType === "error") {
+        console.error(res.msg);
+        process.exit(1);
+      }
+    }, function (err) {
+      // If the file doesn't exist, that's fine
+      if (err && err.code !== "ENOENT") {
+        throw err;
+      } else {
+        startInsect();
+      }
+    });
+  })();
 } else {
   startInsect();
 }

package.json

@@ -18,16 +18,18 @@
     "test": "test"
   },
   "files": [
-    "output",
+    "insect.js",
     "web/media/insect.png"
   ],
   "scripts": {
     "setup": "npm run build",
     "start": "node copy && run-p server esbuild:watch",
-    "esbuild:watch": "spago build -w --then 'npm run esbuild'",
-    "esbuild": "esbuild output/Insect/index.js --bundle --minify --outfile=web/insect.js --target=es6 --global-name=Insect",
+    "esbuild:watch": "spago build -w --then 'npm run esbuild:browser'",
+    "esbuild": "npm run esbuild:browser && npm run esbuild:node",
+    "esbuild:browser": "esbuild output/Insect/index.js --bundle --minify --outfile=web/insect.js --target=es6 --global-name=Insect",
+    "esbuild:node": "esbuild output/Insect/index.js --bundle --minify --outfile=insect.js --target=node12 --platform=node --format=esm --external:./node_modules/*",
     "build": "spago build && npm run esbuild && node copy",
-    "prepack": "npm run build",
+    "prepack": "spago build && npm run esbuild:node",
     "server": "live-server web --open",
     "test": "spago test"
   },