Fixed netcdf-c issue #30 (on github) related to cmake-generated nc-config script.

Initial split of Guide from rest of documentation.  Using 'tagfiles' to cross-reference from one documentation set to the other works, but then it drags all of the 'external' related pages into the index of the other.

Modified visability of the external groups and pages.

Adding proper section names to 'Example' sections, to avoid Doxygen warnings.

Initial split of Guide from rest of documentation.  Using 'tagfiles' to cross-reference from one documentation set to the other works, but then it drags all of the 'external' related pages into the index of the other.

Modified visability of the external groups and pages.

Adding proper section names to 'Example' sections, to avoid Doxygen warnings.

Reorganizing documentation into two separate doxygen projects.

Moved .texi documents into an old directory.

Pulled the tutorial document into a separate document, similar to the guide document.

Turned on treeview
Merge branch 'sub_doc' of https://github.com/Unidata/netcdf-c into sub_doc

Conflicts:
	man4/guide.dox