This commit marks the CreateMessage and CreateMessageWithId functions as
deprecated as they are no longer maintained due to the new concrete
command approach.
It also updates the package documentation to show the new preferred method
as well as add details about btcd.
ok @jcvernaleo
This commit makes the examples a little more clear by providing complete
examples of the two different types of replies. These changes were
prompted by PaulCapes on IRC who pointed out the previous example was not
very clear.
ok jcv@
