dm: archive old files before upload new ones
backup: don't move directory
lazycat: split and rename 'which' to 'cmd_exists'
lazycat: split and rename common messages printing
lazycat: split out "log" part
lazycat: remove unimplemented DNS diag codes

Move them to TODO list.
lazycat: split out history command save/restore codes
lazycat: fix by advice of PEP
lazycat: simplify codes

Drop a lot unnecessary try-except sentences.
lazycat: start to moving to python3

Split out "show" function.
lazycat: completely moved to python 3

There's a lot plumber changes.
Merge branch 'lazycat-python3' into devel
lazycat: finished multi-level completer
lazycat: move virtual tty to lib/
print help and return when there's no arguments for ssh/telnet
TODO updates
lazycat 0.2
Merge branch 'devel'
Revert "lazycat 0.2"

This reverts commit 89b73656cacee660efe9db26bfce0c96145ba2dc.
lazycat 0.2