[GRASS5] Programmer's manual -> source code (doxygen)

[Markus Neteler]

The last days I have almost finished the migration
of the Programmer's manual into the source code 
(based on doxygen):

- inserted docs for around 800 functions in 230 files.
- TODO: add/finish the general explanations pages such
  as src/libes/gis/gisrasterlib.dox
  (also a very boring job)
- clean out docs where the function no longer exists
  (orphaned explanations)

In future we'll be able to extract the progman just by
launching

G53: make docs

G57: make htmldocs (or)
     make pdfdocs

I'll make that a cronjob later to update the web site
automatically on a weekly/monthly base.

My hope is that the maintainance of the programmer's manual
will be easier since the docs are now as close as possible
to the functions.

Hope this helps (also to get new developers :-)

 Markus