Merge remote-tracking branch 'remotes/elmarco/tags/option-pull-request' into staging

CLI help improvements

PULLv2:
 - fix uninitialized "seentype" variable in qom-test

# gpg: Signature made Fri 05 Oct 2018 13:28:21 BST
# gpg:                using RSA key DAE8E10975969CE5
# gpg: Good signature from "Marc-André Lureau <marcandre.lureau@redhat.com>"
# gpg:                 aka "Marc-André Lureau <marcandre.lureau@gmail.com>"
# Primary key fingerprint: 87A9 BD93 3F87 C606 D276  F62D DAE8 E109 7596 9CE5

* remotes/elmarco/tags/option-pull-request:
  vl: list user creatable properties when 'help' is argument
  hostmem: add some properties description
  vl: handle -object help
  tests/qom-proplist: check class properties iterator
  tests/qom-proplist: check properties are not listed multiple times
  tests/qom-proplist: check duplicate "bv" property registration failed
  qom/object: register 'type' property as class property
  qom/object: fix iterating properties over a class
  qemu-option: improve qemu_opts_print_help() output
  qemu-option: add help fallback to print the list of options
  cutils: add qemu_pstrcmp0()
  qdev-monitor: print help to stdout

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>