Update list of loaders to remove unmaintained and deprecated

[atdiff]

The list of loaders includes some projects that are outdated, unmaintained, and/or deprecated. For instance, these two projects are both listed for Typescript and are no longer maintained:

• https://github.com/denvned/webpack-typescript
• https://github.com/andreypopp/typescript-loader

To limit confusion, it'd be great if the list were cleaned up a little. Or at least identify the status of the projects, provide a last updated date, or something along these lines.