- Derivatives are now assembled in a slightly different manner (i.e. they

- Derivatives are now assembled in a slightly different manner (i.e. they
  'look' different on first sight).  Under certain circumstances this can
  result in a dramatic speedup because it gives hashing a better chance,
  especially when computing higher derivatives.
- Series expansion accepts an additional bool argument now, telling it
  whether branch cuts are to be honored (as Maple does it) or not (as
  Mathematica does it).  It defaults to true (i.e. the Maple way).
- Many series expansions of built-in functions have been reengineered.
- The Dilogarithm (Li2) now has floating point evaluation, derivative and a
  proper series expansion.
- Namespace 'std' cleanly disentangled, as demanded by ISO/EIC 14882-1998(E).
- Some helpers updated from upstream.