[vsipl++] patch: Enhance doc building

[Jules Bergmann]

Stefan Seefeld wrote:
> The attached patch adds all doc/tutorial/*.xml files explicitely as dependencies,
> and adds convenience targets doc_manuals, html_manuals, and pdf_manuals.
> 

Stefan, this looks good, please check it in (if you haven't already), 
thanks -- Jules

-- 
Jules Bergmann
CodeSourcery
jules at codesourcery.com
(650) 331-3385 x705