Implement "secure" PathCch* shell functions

Starting Windows 8 the following PathCch* functions: https://msdn.microsoft.com/en-us/library/windows/desktop/dd807193(v=vs.85).aspx provide more "secure" variants than their Path* equivalents, in the sense that they also take in input the size in characters of the string buffer passed in argument.
They appear to be implemented in a library Pathcch.lib, and defined in a header Pathcch.h.