+/**
+ \brief Common constuctor for RSETs
+ \param sel The interface control handle
+ \param nmem The memory handle for it.
+ \param kcontrol Key control info (decode, encode, comparison etc)
+ \param scope scope for set
+ \param term Information about term for it (NULL for none).
+ \param no_children number of child rsets (0 for none)
+ \param children child rsets (NULL for none).
+
+ Creates an rfd. Either allocates a new one, in which case the priv
+ pointer is null, and will have to be filled in, or picks up one
+ from the freelist, in which case the priv is already allocated,
+ and presumably everything that hangs from it as well
+*/