Updated Docbook5 with webhelp target (finally..)

Hi,

I have now updated the docbook5 build process to work with the very latest DocBook stylesheets (1.78.1) this means that the elusive webhelp target is finally added!

All updates are under the directory "docs/docbook5"

Apart from some "look-and-feel" tweaks for the webhelp output the migration to DocBook5 is now complete and it is up to you to decide when you want to switch to using this as the main documentation.

Johan