Rename FILE_TYPE_UNKNOWN to HPLIBS_FILE_TYPE_UNKNOWN, so as to fix a conflict between a definition in winbase.h and the definition in filetypes.h.

Signed-off-by: Lionel Debroux <lionel_debroux@yahoo.fr>
Add support for "send key" operation.

Signed-off-by: Lionel Debroux <lionel_debroux@yahoo.fr>
Tested-by: Xavier "critor" Andréani <andreanx@hotmail.com>