This moves some data from README to the man pages and has other general
improvements.

This patch adds a man page for hscan and updates the README and other
man pages with the latest changes.

This patch adds a new n_mem field to the node objects, and implements
read/save/show support for it. The field is not currently used (except
in the node list) but will be used for checking data consistency and
instance up/down status.

This patch adds a new ‘-’ flag for the node status which denotes offline
nodes.

A new man page and typos fixed in hbal.1.