Filename exclusion (with -i) works only for the source files.
Print a warning if user tries to exclude header file. The warning
instructs user to use --suppress for ignoring warnings from the
header files.
simplifyPath() "fits" better to Path class conceptually. It handles
paths, not lists them. Also this way we get rid of few unneeded
dependencies to FileLister class.
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.