Remove man pages and other pages which 'make clean' did not remove
before.
To evaluate which pages could be removed, I did a full build and
check, and then ran 'make clean' followed by 'git clean -xdf'. By
examining the output of the git clean command I could see which files
were being missed.
Files that are _not_ removed by make clean or make distclean:
- generator-built files
- Makefile, Makefile.in, .deps, .depend
- any ./configure output files (maybe they should be?)