Fixed several Doxygen warnings, limited input to *.hpp files

doc/doxyfile.in

@@ -591,30 +591,7 @@ INPUT_ENCODING         = UTF-8
 # *.c *.cc *.cxx *.cpp *.c++ *.java *.ii *.ixx *.ipp *.i++ *.inl *.h *.hh *.hxx 
 # *.hpp *.h++ *.idl *.odl *.cs *.php *.php3 *.inc *.m *.mm *.py *.f90
 
-FILE_PATTERNS          = *.c \
-                         *.cc \
-                         *.cxx \
-                         *.cpp \
-                         *.c++ \
-                         *.d \
-                         *.java \
-                         *.ii \
-                         *.ixx \
-                         *.ipp \
-                         *.i++ \
-                         *.inl \
-                         *.hh \
-                         *.hxx \
-                         *.hpp \
-                         *.h++ \
-                         *.idl \
-                         *.odl \
-                         *.cs \
-                         *.php \
-                         *.php3 \
-                         *.inc \
-                         *.dox \
-                         *.py
+FILE_PATTERNS          = *.hpp
 
 # The RECURSIVE tag can be used to turn specify whether or not subdirectories 
 # should be searched for input files as well. Possible values are YES and NO.