minor code style fix
fix losing file description after error
Engine::Copy: copy process was cancelled after Skip command
refactoring: FClose: check parameter
use memory buffer 4MB for file operations by default

(http://forum.farmanager.com/viewtopic.php?p=124729#p124729)
refactoring: enum TOverwriteMode
refactoring: rename fields
version info: update
cleanup
refactoring: rename fields