+ * new feature: SB-EXT:TYPEXPAND-1, SB-EXT:TYPEXPAND, and
+ SB-EXT:TYPEXPAND-ALL behave exactly like their MACROEXPAND counterparts
+ but work on type specifiers.
+ * new feature: SB-EXT:DEFINED-TYPE-NAME-P returns whether a symbol is known
+ to name a type specifier.
+ * new feature: SB-EXT:VALID-TYPE-SPECIFIER-P returns whether a given type
+ specifier is valid where "valid" basically means "would be accepted as
+ second argument of TYPEP".
+ * new feature: SB-INTROSPECT:FUNCTION-TYPE takes a function-designator and
+ returns the function's declared, or derived FTYPE.