In this initial commit the Path class contains two methods for
converting path separators. I want to move cppcheck path handling
to direction that we internally have paths with / separator. And
convert from/to native separators when needed.
Improve the system used to have separate versions of code of FileLister for
Win32 and Linux. New idea is to have Base FileLister class implementing
common code and then derived classes for Win32 and Linux specific code.
FileLister is not anymore a static class. Instead we use singleton of
derived class.