this here brings one new top level target which is doc. It is not build
by default, and does rerun everything on every call.
ninja doc will create previews and run the doxygen command. After this
is done, a tarbal of the html & man will be created, latex is not added
for now, due to the unability to compile the resulting .tex files.
Nothing of the documentation is installed for now, if this would be
enabled, then every single ninja install would regenerate the whole
documentation again, which is quite a lot, and quite a pain (and
While porting this over, i encountered a problem with *convert* the bug
report is linked in the comment.
Depends on D8690