#173 installation of manual pages and html documentation

[J G Miller]

For the latest giflib v 5.2.2, the supplied makefile builds the manual pages and the HTML documentation but when it comes to installation, make install just puts all the manual page source xml files in "$(DESTDIR)$(MANDIR)/man1" which is surely incorrect. Each built manual page (.1, .7) should be installed in the correctly numbered man subdirectory and it would be great if make install also installed the html files to something like ""$(DESTDIR)/share/doc/giflib/html".

Thanks!

[Eric S. Raymond]

Fix pushed,