Provide some input filters for making links, along with an optional CKEditor plugin.

In two words, you can either write one of:

• html <a href="entity:node/12">Some entity</a>
• html <a href="entity://node/12">Some entity</a>
• html <a href="{{node/12}}">Some entity</a>

in any text that would be php check_markup()'ed and filters will be processed and turned into correct Drupal URL or URL aliases.

The CKEditor plugin requires ckeditor >= 4.

You may use url('entity://node/12') to generate the node link, there is an hook_url_outbound_alter implementation that will do the job.