PathComp: use absoluteFilePath() instead of canonicalFilePath()

canonicalFilePath() return an empty string if a file does not exist.
PathComp: convert a drive letter to the upper case in toNativePath()
PathComp: rename toNativePath() to nativePath()
KFileWizard: distinguish a native path and a canonical path

And use PathComp member functions directly
Support directory copy
PathComp: introduce addDirSeparator() and removeDirSeparator()
KFileWizard: check a running status of a thread before enter into a loop
Support to remove directories
FileOperation: add mkdir() and rmdir() member functions
KFileWizard: fix getNameOfCopy() does not work with ftp path without .

For examples, getNameOfCopy() return ftp://192.168.10 -
Copy.104/ftp/incoming/test for ftp://192.168.10.104/ftp/incoming/test.
FtpBuffer: add some useful debugging messages
FtpFileEngine: implement mkdir() and rmdir()

And call QDir() with a ftp path so that FtpFileEngine is called.
FtpTransferThread: Use a separate instance only for writing

Too many instances causes a transfer to fail. So minimize used instances
if possible.
KFileWizard: set range of a progress dialog for removing correctly
FtpSync: clear _ftpDone on setFtp()
FtpFileEngine: exclude non-existent entries in beginEntryList()
FtpFileEngine: refresh automatically

And disable manual refresh
KFileWizard: reflect directory changes to dirModel and locationComplter
KFileWizard: disable unnecessary refresh
FtpFileEngine: prevent buffer from growning up too large