Remove any variables in the optional build variable list that are marked as mandatory by one or more included build system modules in the CORE build system module. Alter DOXYGEN build system module to by default override the Doxygen configuration file stylesheet and replace it with the LUFA Doxygen stylesheet.

LUFA/Build/lufa.core.in

@@ -76,7 +76,7 @@ help: info
 	@echo "                                                                   "
 	@echo "  Optional variables required by the selected build Modules:       "
 	@echo "                                                                   "
-	@echo "    [" $(sort $(LUFA_BUILD_OPTIONAL_VARS)) "]"
+	@echo "    [" $(filter-out $(LUFA_BUILD_MANDATORY_VARS), $(sort $(LUFA_BUILD_OPTIONAL_VARS))) "]"
 	@echo "                                                                   "
 	@echo "==================================================================="
 	@echo "        The LUFA BuildSystem 2.0 - Powered By Unicorns (tm)        "
@@ -92,4 +92,4 @@ list_mandatory:
 	@echo Mandatory Variables for Included Modules: $(sort $(LUFA_BUILD_MANDATORY_VARS))
 	
 list_optional:
-	@echo Optional Variables for Included Modules: $(sort $(LUFA_BUILD_OPTIONAL_VARS))
+	@echo Optional Variables for Included Modules: $(filter-out $(LUFA_BUILD_MANDATORY_VARS), $(sort $(LUFA_BUILD_OPTIONAL_VARS)))