clipboard: add events for file clipping.
clipboard: implement file clipping on XP.
    add temp directory.
    use %TEMP% directory as file transfering temprorary directory.
    if %TEMP% directory is in C:\, driver C:\ should be redirected in order
    to enable file clipping on XP.
clipboard: wfreerdp: add COM objects for file clipping.
clipboard: wfreerdp: implement COM objects for file clipping.
wfreerdp: fix warning.
clipboard: wfreerdp: implement file clipping.
Merge pull request #1732 from zhangzl2013/file-clipping

File clipping