* Put current version of babel-types in the root
Previously, the code that supports the oldest version of Typescript was in the root: 3.1 and below. Newer versions were in ts*/ subdirectories.
This PR puts the newest version in the root, and older versions -- before 3.7 in this case -- in ts*/ subdirectories. This is possible because all supported versions of the Typescript now understand the typesVersions property in package.json.
This PR needs a new version of DefinitelyTyped-tools and dtslint, which I will ship soon. It also needs to be brought up to date with master.
* delete ts3.7/
* use correct relative reference for test
Note that this *trivially* updates project urls by adding the NPM url to
the end, even when the urls are almost identical or the DT one is
outdated. I'll clean up the urls in a later commit.
This PR is unfinished! Please do not merge it yet.
e.g. this named declaration has a source:
```javascript
export {foo} from './bar.js';
```
and this one does not:
```javascript
export const foo = 10;
```
Try it out at https://astexplorer.net/ to confirm.
