improve performance in linalg.py; cosmetic code changes
improve performance in linalg.py; cosmetic code changes

This is achieved by using fsum(), list comprehensions and generators.
Some unnecessary whitespaces were removed.


JensGrabner/mpmath,bjodah/mpmath,bjodah/mpmath,klkuhlm/mpmath,JensGrabner/mpmath,klkuhlm/mpmath,fredrik-johansson/mpmath