This means that typedef struct SomeStruct {...} SomeStruct will only be
documented as SomeStruct in the doxy, without a pointless entry in the
typedefs list.
The options USE_INLINE_TREES, SHOW_DIRECTORIES and HTML_ALIGN_MEMBERS
became obsolete with doxygen 1.8.1 (releaded 2012-05-19). The generated
outpu for older doxygen versions should not change since they were set
to the default value.