Fix cdup issue when directory not found
Add set-host utility

Helper to update /etc/hosts which handily accepts DNS names
(whereas /etc/hosts only accepts IP addresses)

Usage: set-host HOST ALIAS

If ALIAS is omitted, it displays the current mapping.
Update .gitignore to exclude vim swap files
Add tm utility (Time Machine)

usage: tm CMD OPTIONS...

	on  PATH       enable time machine for PATH
	off PATH       disable time machine for PATH
	status [PATH]  inquire status of PATH or current dir if omitted