revset: made ascgeneratorset a private class This class is not supposed to be used outside revset.py since it only wraps content that is used by baseset typed classes. It only gets created by revset operations or private methods.

revset: made generatorset a private class This class are not supposed to be used outside revset.py since it only wraps content that is used by baseset typed classes. It only gets created by revset operations or private methods.

cmdutil: changed walkchangerevs to use spanset instead of baseset Using a spanset takes almost no memory at all. A baseset builds the entire list in memory and is much slower for methods like __contains__.