1. Strip end spaces and slashes
2. Do NOT change dir if in the same dir
3. Don't go back beyond startup dir with '-'
4. Reset oldpath on cd (other than cd . and ..)
5. Reset filter
6. Update features in README

This change remaps the & key. However, / is more relevant for filter and & makes more sense wrt. address.

With the features the readline library provides it would be too naive to ignore.
We break out of the curses mode into the prompt and get back in.
This change introduces dependency on libncurses.

Update README on dependencies

Calculation can take very long. Most Unix-ish OSes have utilities to do this.

It was troubling me. Mimicking 'gg' would have been hacky and would need
additional processing... 'g' was free. Who cares even if you press twice? ;)