Qt跨平台路径表示法

跨平台开发的时候，经常涉及到路径的表示问题，有单斜杠、双斜杠、双反斜杠等等，很容易出问题，所以直接用separator()方法代替斜杠即可，API原文：

QChar QDir::separator()
  
Returns the native directory separator: "/" under Unix and "\" under Windows.
You do not need to use this function to build file paths. If you always use "/", Qt will translate your paths to conform to the underlying operating system. If you want to display paths to the user using their operating system's separator use toNativeSeparators().
See also listSeparator().