gnucash 3.0 installation

[James Russell Kuyper Jr.]

I'm trying to build gnucash 3.0 on a machine running Ubuntu Linux 16.04,
following the instructions provided at
<https://wiki.gnucash.org/wiki/Building#Ubuntu_16.04_LTS_.28Xenial_Xerus.29>.
I had no problems until I got down to the step which says:

cmake -D CMAKE_INSTALL_PREFIX=<target>/gnucash-cmake -D
WITH_AQBANKING=OFF -D WITH_OFX=OFF ../gnucash

I'm not entirely clear what <target> should be. I looked an found that
my current version off GnuCash, 2.6.5, was installed at
/usr/lib/x86_64-linux-gnu/gnucash. I removed that version, and used the
following command, with the following results:

~/Downloads/gnucash-3.0/build-cmake(133) sudo cmake -D
CMAKE_INSTALL_PREFIX=/usr/lib/x86_64-linux-gnu/gnucash/gnucash-cmake -D
WITH_AQBANKING=OFF -D WITH_OFX=OFF ../gnucash
-- Performing Test have_mod_mask
-- Performing Test have_mod_mask - Failed
CMake Error at gnome/CMakeLists.txt:59 (gnc_add_swig_guile_command):
  Unknown CMake command "gnc_add_swig_guile_command".


CMake Warning (dev) in CMakeLists.txt:
  No cmake_minimum_required command is present.  A line of code such as

    cmake_minimum_required(VERSION 3.5)

  should be added at the top of the file.  The version specified may be
lower
  if you wish to support older CMake versions for this project.  For more
  information run "cmake --help-policy CMP0000".
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Configuring incomplete, errors occurred!
See also
"/home/james/Downloads/gnucash-3.0/build-cmake/CMakeFiles/CMakeOutput.log".
See also
"/home/james/Downloads/gnucash-3.0/build-cmake/CMakeFiles/CMakeError.log".

Any suggestions?