unix.linux.proc: Refactor /proc parsing. Add generic to make pid/string and pid-string/string pairs into /proc/pid/pathname.
tools.ps: Use unix.linux.proc for parsing.
calendar.format: Add some utility words for implementing top.
unix.linux.proc: Add some more /proc parsing.
unix.linux.proc: Older kernels don't have enough fields in /proc/pid/stat. Pad it.