Remove obsolete Doxyfile declarations

Signed-off-by: Allan McRae <allan@archlinux.org>

doc/Doxyfile.in

@@ -205,7 +205,6 @@ EXT_LINKS_IN_WINDOW    = NO
 OBFUSCATE_EMAILS       = YES
 HTML_FORMULA_FORMAT    = png
 FORMULA_FONTSIZE       = 10
-FORMULA_TRANSPARENT    = YES
 FORMULA_MACROFILE      =
 USE_MATHJAX            = NO
 MATHJAX_VERSION        = MathJax_2
@@ -313,8 +312,6 @@ DIA_PATH               =
 HIDE_UNDOC_RELATIONS   = YES
 HAVE_DOT               = YES
 DOT_NUM_THREADS        = 0
-DOT_FONTNAME           = Helvetica
-DOT_FONTSIZE           = 10
 DOT_FONTPATH           =
 CLASS_GRAPH            = YES
 COLLABORATION_GRAPH    = YES
@@ -342,7 +339,6 @@ PLANTUML_CFG_FILE      =
 PLANTUML_INCLUDE_PATH  =
 DOT_GRAPH_MAX_NODES    = 50
 MAX_DOT_GRAPH_DEPTH    = 3
-DOT_TRANSPARENT        = NO
 DOT_MULTI_TARGETS      = NO
 GENERATE_LEGEND        = YES
 DOT_CLEANUP            = YES