Support fractional seconds (and other time units) in `top -d`.
LTP uses `top -d 0.1`, which isn't convincingly useful, but general
support for other time units might be useful, and switching to xparsetime
addresses both at once.
Also fix 3169d948c049664bcf7216d4c4ae751881099d3e where I mistakenly
treated `rev` and `toys.optflags&FLAG_b` as interchangeable. (Without
this second fix, `top -b` looks fine but `top` is broken!)
Also fix xparsetime to reject input such as "monkey" or "1monkey".
3 files changed
