Naive implementation of help, linking to the wiki

Fixes #1423

Squashed commit of the following:

commit ad81610ee1721257577771e8443172f448bcc541
Author: Kazark <kazark@zoho.com>
Date:   Wed Aug 27 11:34:29 2014 -0400

    Link to the wiki on :help even if topic specified

commit a4bcff8565520f66db2b169b718d82a5f15fe0af
Author: Kazark <kazark@zoho.com>
Date:   Wed Aug 27 11:24:24 2014 -0400

    First step to implementing naive :help command