Properly reimplement shell operations - in the shell = None path

• CoSaves - remove this class and integrate cosaves moving in SaveInfos - must be atomic! See ugly hacks in basher.SaveList#OnLabelEdited
• absorb move_info in move_infos - use shellMove
• collisions handling - partially done in b5bb441: collisions are detected and prompted for, but auto-renaming is not implemented).
• document parameters - done in b5bb441
• care for unix - see for instance the globbing code in BAIN Installers does not install all files #96 - done in b5bb441 and 2f72224
• We should take advantage of reflinks on COW filesystems for free copies - see https://pypi.org/project/reflink and shutil: add reflink=False to file copy functions to control clone/CoW copies (use copy_file_range) python/cpython#81338 - done in f2f5450
• use IFileOperation (hard! - see my fork repo: https://github.com/Utumno/wrye-bash/tree/IFileOperation) - done in b5bb441
• Paths ! Rewrite taking care to be unix friendly - see for instance the drive() method -> new issue Path API #368