ENH: Generate tarball of SlicerWizard doc

Create a new build target to generate a tarball of the SlicerWizard
documentation. This is meant to be used similar to the existing Doxygen
tarball, to be scp'd or otherwise transferred from a build machine to
another machine which will serve the pages publicly.

Issue #3601

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23209 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: Refactor documentation targets

Replace generate_userdoc.cmake script with direct build commands,
separating creation of the doc and creation of the tarball thereof into
separate targets, for consistency with how the SlicerWizard doc build
rules are set up. Also modify the latter to explicitly remove the old
tarball first for consistency with (the historic and retained behavior
of) the former.

The old rules depended on the output index.html, which would cause them
to do nothing once the doc had been created (ever). The new rules, like
the rules for the SlicerWizard doc, have no dependencies and so the doc
is always regenerated when the target is traversed. As doxygen
unfortunately does not implement its own dependency tracking (sphinx
does), this is very inefficient, but more correct, which is more
important for this case.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23210 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Fix cpp documentation names

The C++ documentation covers all of Slicer, not just Base. Therefore,
fix the tarball name and target names (the latter of which have been
"wrong" since a while back).

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23211 3bd1e089-480b-0410-8dfb-8563597acbee