Use TypeScript project reference (#1002)

* Add *.tsbuildinfo to .gitignore

* Bump versions of dependencies, nyc and yargs

* Drop support for node 9 (EOL 2018-06-30)

https://github.com/nodejs/Release

* Add getTransaction snippet

snippets/src/parseAccountFlags.ts

@@ -0,0 +1,13 @@
+import {RippleAPI} from '../../dist/npm'
+
+const api = new RippleAPI({server: 'wss://s.altnet.rippletest.net:51233'})
+
+parseAccountFlags()
+
+async function parseAccountFlags() {
+  await api.connect()
+  const account_info = await api.request('account_info', {account: 'rKsdkGhyZH6b2Zzd5hNnEqSv2wpznn4n6N'})
+  const flags = api.parseAccountFlags(account_info.account_data.Flags)
+  console.log(JSON.stringify(flags, null, 2))
+  process.exit(0)
+}