Limit all xstrlcpy() calls by dest length.
Escape filenames in system(3) calls.

We are converting multi-byte to wide char and vice versa to replace the escape
chars with ?. Otherwise we run the risk of breaking a Unicode code point.

* Add automatic RPM builds via travis

* readline.h must be imported after stdio.h to pick up def of FILE

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

Add definition of PATH_MAX on GNU/Hurd

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