Fix issue 46: Error when doxygen is missing
Fix issue 46: Error when doxygen is missing

libroxml will now skip the documentation generation if doxygen is not found.

gergap/libroxml,mahmudur85/libroxml,sartura/libroxml,gergap/libroxml,mahmudur85/libroxml,gergap/libroxml,gergap/libroxml,mahmudur85/libroxml,mahmudur85/libroxml,sartura/libroxml,sartura/libroxml,mahmudur85/libroxml,sartura/libroxml,sartura/libroxml,gergap/libroxml