Problem 144 added, utils.py edited.

Yay! Problem 144 solved, it was a nice one. Some geometric functions
were added to utils.py:

*)  Point rotation against a given center and angle (in radians).
*)  Line rotation against a given center and angle (in radians).
*)  Matrix multiplication with a vector.
*)  Check if a point lies in a given line.
*)  Solve a quadratic equation given its coefficients.
*)  Some basic matrix-vector operations (check for duplicates when
    refactoring).