Pebble/Jade/Thymeleaf/Rocker/Freemaker template engines support

**Is your feature request related to a problem? Please describe.**
Knot.x Template Engine supports Handlebars syntax. Other engines can be utilised:
- Freemarker
- Jade
- mvel
- Pebble
- Rocker
- Thymeleaf

**Describe the solution you'd like**
Use Vert.x modules inside Knot.x Template Engine: https://github.com/vert-x3/vertx-web/tree/master/vertx-template-engines.

Read the existing Handlebars support and the linked Vert.x template-engine modules first. Confirm the integration scope for Freemarker, Jade, MVEL, Pebble, Rocker, and Thymeleaf; done means the requested engines are supported by Knot.x Template Engine.

Written by the indexing model from the issue text.