Summary: Checking of coding styles

Description:
Allows automated checking of coding styles. Coding styles can be specified
flexibly in an external file. This is a major update to this extension,
including:

* Now uses the latest Checkstyle release, v4.3
* Simpler one-jar installation
* Allows configuration files to be read from URLs in addition to local files
* The documentation has additional tips useful for lab-based or cloned setup

Maintainer: nobody