attempt at improving file list losses on windows: reduced auto-save delay for file list to 5 mins, removed auto-save when new sources are added, added WRITE_THROUGH flag for call to MoveFileEx to ensure the write is finished before moving the file. To be tested.

git-svn-id: http://svn.code.sf.net/p/retroshare/code/branches/v0.5.5@7487 b45a01b8-16f6-495d-af2f-9b41ad6348cc