+ * optimization: COUNT on bitvectors now operates word-at-a-time.
+ * optimization: ASH with a positive, but not necessarily constant,
+ (leftwards) shift, when in a modular context, is compiled to a
+ hardware shift.
+ * fixed some bugs revealed by Paul Dietz' test suite:
+ ** FORMAT variable parameters ("~V<char>") are defaulted properly
+ if the corresponding argument is NIL.
+ ** FORMAT directives accepting a minpad parameter treat negative
+ values as 0.
+ ** literal commas as character parameters to FORMAT directives are
+ parsed correctly.
+ ** literal spaces directly after ~<Newline> directives within a
+ format-logical-block (~:< ~@:>) do not induce :FILL-style
+ conditional newlines.
+ ** PRINT-UNREADABLE-OBJECT inserts spaces as specified (and only
+ as specified: it no longer includes conditional newlines).
+ ** PRINC-TO-STRING binds *PRINT-READABLY* to NIL (as well as
+ *PRINT-ESCAPE*).
+ ** PPRINT-LOGICAL-BLOCK signals a TYPE-ERROR if its :PREFIX or
+ :PER-LINE-PREFIX argument does not evaluate to a string.