Exports some procs at nimrod level. Refs #6.

Also avoids repeated configuration loading through global.
Adds include unit tests. Refs #6.
Adds incldue support with base directory. Refs #6.

Also adds logging.nim for debug versions of the plugin.
Modifies nakefile to use own rst generator. Refs #6.
Notes task in changes log. Refs #6.
Merge branch 'feature/t6_include_directive' into develop
Mentions task in changes log. Refs #7.