Problems found using the rule checker:

1.  The Number classes all overrode #~=.
    They didn't need to do that in order to produce correct results;
    it was an efficiency hack.
    But without them, the compiler could inline Object's definition
    	x ~= y
    =>	(x = y) not
    which should eventually be even better.

2.  SequencedReadableCollection defined #=
      ReadOnlyString inherited it
        String inherited it too
        Symbol overrode it
    The effect was that
	x := "foo".
	y := String withAll: x.
	x = y
    returned false, whereas in Smalltalks without ReadOnlyString it
    would be expected to return true.  Now
      {ReadOnlyString|String} = {ReadOnlyString|String}
    is allowed and works on the contents, but it remains true that
    Symbols are only ever equal to other Symbols.

3.  In Collections, c notEmpty is the same as c isEmpty not,
    so you get used to the idea that you can use whichever of isEmpty
    or notEmpty is clearer in context.
    However several kinds of Stream defined #isEmpty without defining
    #notEmpty.  

4.  The other indexed collections supported atAll:put: as well as at:put:.
    Dictionary didn't, and there's no reason why it couldn't.

5.  I wanted to provide a new (indexableCollection at: key exchange: newValue)
    method which would return the old value.  The main purpose was to remove
    elements from an array, e.g., x := array at: i exchange: nil
    and to halve the cost of index checking for this.  The rule checker
    told me about all the classes that needed the new method.

6.  Knowing that Duration>>isZero and Duration class>>zero existed, and
    that #isZero existed for numeric classes, I expected that #zero
    would exist as well, e.g., FloatD zero.  But it doesn't!
    I've added zero and one methods to the number classes in complex.st

7.  In addition to #withAll:, I have provided #withAll:collect: methods
    in the relevant collection classes.  However, some of them turned out
    to be missing.

8.  I have some numeric vector classes meant long term to be a BLAS-1
    wrapper.  These things are supposed to have all the appropriate
    numeric methods, but they do not and cannot inherit from Number.
    They were missing #negated.

9.  Point and Rectangle had #rounded and #truncated
    but not #floor or #ceiling.  Point acts a lot like a 2-vector;
    it was also missing #raisedTo: and #raisedToInteger:.

10. A new method from:to:valuesDo: had been added to the classes where
    it was needed for something else, but not to all the classes where
    it made sense.

11. A new collection class could remove one thing at a time but not
    everything at once.

12. Two new stream classes had the general #position: method for
    repositioning but not the useful shorthand #reset for moving
    to the beginning.

13. FileStream had peek but not peekFor:, and so did DecodedInputStream.

14. NDBM class defined useless #withAll:[collect:] methods.  They are NOT
    needed to prevent unsuitable methods being inherited; removing them
    means that NBDM class does not have any such methods at all.