Unset NEWPWD, so it doesn't get put into the zsh prompt
Spaces in dirname work, and case-insensitive matching: use -si
Updated README to reflect case-insensitive update
Updated usage message to include -si option
chmod +x
Add shorter usage message.

Long usage is only printed when -h is given.
Merge remote-tracking branch 'rmhsilva/master'

Conflicts:
	README.md