updated documentation

- fixed smaller doxygen bugs
- merged boundary.html (from the workshop) into IntersectionIterator docu

[[Imported from SVN: r349]]

doc/doxygen/Doxyfile

@@ -362,14 +362,7 @@ WARN_LOGFILE           =
 # with spaces.
 
 INPUT                  = mainpage \
-                         ../../grid \
-                         ../../disc \
-                         ../../fem \
-                         ../../common \
-                         ../../quadrature \
-                         ../../solver \
-                         ../../istl \
-                         ../../io
+                         ../../grid
 
 # If the value of the INPUT tag contains directories, you can use the 
 # FILE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp