Doxygen: fix warnings + minor improvements to HTML output

doc/Doxyfile

@@ -1017,7 +1017,7 @@ VERBATIM_HEADERS       = YES
 # generated with the -Duse-libclang=ON option for CMake.
 # The default value is: NO.
 
-CLANG_ASSISTED_PARSING = NO
+#CLANG_ASSISTED_PARSING = NO
 
 # If clang assisted parsing is enabled you can provide the compiler with command
 # line options that you would normally use when invoking the compiler. Note that
@@ -1025,7 +1025,7 @@ CLANG_ASSISTED_PARSING = NO
 # specified with INPUT and INCLUDE_PATH.
 # This tag requires that the tag CLANG_ASSISTED_PARSING is set to YES.
 
-CLANG_OPTIONS          =
+#CLANG_OPTIONS          =
 
 #---------------------------------------------------------------------------
 # Configuration options related to the alphabetical class index
@@ -1187,7 +1187,7 @@ HTML_TIMESTAMP         = YES
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_DYNAMIC_SECTIONS  = NO
+HTML_DYNAMIC_SECTIONS  = YES
 
 # With HTML_INDEX_NUM_ENTRIES one can control the preferred number of entries
 # shown in the various tree structured indices initially; the user can expand
@@ -1416,7 +1416,7 @@ DISABLE_INDEX          = NO
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-GENERATE_TREEVIEW      = NO
+GENERATE_TREEVIEW      = YES
 
 # The ENUM_VALUES_PER_LINE tag can be used to set the number of enum values that
 # doxygen will group on one line in the generated HTML documentation.
@@ -2314,7 +2314,7 @@ DIRECTORY_GRAPH        = YES
 # The default value is: png.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-DOT_IMAGE_FORMAT       = png
+DOT_IMAGE_FORMAT       = svg
 
 # If DOT_IMAGE_FORMAT is set to svg, then this option can be set to YES to
 # enable generation of interactive SVG images that allow zooming and panning.