Review comments for the fast reload feature (#1259)

Review comments for the fast reload feature (#1259)

* - fast-reload review, respip set can be null from a view.

* - fast-reload review, typos.

* - fast-reload review, keep clang static analyzer happy.

* - fast-reload review, don't forget to copy tag_actions.

* - fast-reload review, less indentation.

* - fast-reload review, don't leak respip_actions when reloading.

* - fast-reload review, protect NULL pointer dereference in get_mem
  functions.

* - fast-reload review, add fast_reload_most_options.tdir to test most
  options with high verbosity when fast reloading.

* - fast-reload review, don't skip new line on long error printouts.

* - fast-reload review, typo.

* - fast-reload review, use new_z for consistency.

* - fast-reload review, nit for unlock ordering to make eye comparison
  with the lock counterpart easier.

* - fast-reload review, in case of error the sockets are already closed.

* - fast-reload review, identation.

* - fast-reload review, add static keywords.

* - fast-reload review, update unbound-control usage text.

* - fast-reload review, updates to the man page.