Project sanity check (#76)

* tslint: CRLF -> LF

* gitignore more build artifacts

* Add proposed .editorconfig

* Allow for "clean" builds

src/ts/generated/ content is still required (sprites.ts,
gamepad-mappings.ts), but src/scripts is not.

* Add --sprites option to production build

* Add note about sprites to README

package-lock.json

@@ -2004,9 +2004,9 @@
       }
     },
     "arg": {
-      "version": "4.1.0",
-      "resolved": "https://registry.npmjs.org/arg/-/arg-4.1.0.tgz",
-      "integrity": "sha512-ZWc51jO3qegGkVh8Hwpv636EkbesNV5ZNQPCtRa+0qytRYPEs9IYT9qITY9buezqUH5uqyzlWLcufrzU2rffdg=="
+      "version": "4.1.1",
+      "resolved": "https://registry.npmjs.org/arg/-/arg-4.1.1.tgz",
+      "integrity": "sha512-SlmP3fEA88MBv0PypnXZ8ZfJhwmDeIE3SP71j37AiXQBXYosPV0x6uISAaHYSlSVhmHOVkomen0tbGk6Anlebw=="
     },
     "argparse": {
       "version": "1.0.9",
@@ -23128,9 +23128,9 @@
       }
     },
     "yn": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/yn/-/yn-3.1.0.tgz",
-      "integrity": "sha512-kKfnnYkbTfrAdd0xICNFw7Atm8nKpLcLv9AZGEt+kczL/WQVai4e2V6ZN8U/O+iI6WrNuJjNNOyu4zfhl9D3Hg=="
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/yn/-/yn-3.1.1.tgz",
+      "integrity": "sha512-Ux4ygGWsu2c7isFWe8Yu1YluJmqVhxqK2cLXNQA5AcC3QfbGNpM7fu0Y8b/z16pXLnFxZYvWhd3fhBY9DLmC6Q=="
     },
     "zone.js": {
       "version": "0.10.2",