Add Doxygen documentation for HEAD.

doxygen/HEAD/all-signals_8h.html

doxygen/HEAD/all-signals_8h__incl.map

doxygen/HEAD/all-signals_8h__incl.md5

doxygen/HEAD/all-signals_8h__incl.png

doxygen/HEAD/annotated.html

doxygen/HEAD/bc_s.png

doxygen/HEAD/class_shell_functions-members.html

doxygen/HEAD/class_shell_functions.html

doxygen/HEAD/class_shell_procedure-members.html

doxygen/HEAD/class_shell_procedure.html

doxygen/HEAD/class_shell_procedure__coll__graph.map

doxygen/HEAD/class_shell_procedure__coll__graph.md5

doxygen/HEAD/class_shell_procedure__coll__graph.png

doxygen/HEAD/classboost_1_1noncopyable.html

...gen/HEAD/classdynamicgraph_1_1_contiifstream-members.html

doxygen/HEAD/classdynamicgraph_1_1_contiifstream.html

doxygen/HEAD/classdynamicgraph_1_1_debug_trace-members.html

doxygen/HEAD/classdynamicgraph_1_1_debug_trace.html

...lassdynamicgraph_1_1_default_cast_registerer-members.html

...n/HEAD/classdynamicgraph_1_1_default_cast_registerer.html