Fixes crash retrieving clipboard string. Refs #7.

Can't use $ with nil values directly.
Adds nakefile to build/check docs. Refs #8.
Moves markdown files to rst. Refs #8.
Adds documentation index. Refs #8.
Updates readme with babel and docindex info. Refs #8.
Fixes rst links.
Merge branch 'feature/t8_docs_in_rst' into develop