top(1): allow filtering by command name

[rew]

Summary

Enable top(1) to filter by command name or command arguments (when they are
being display).

While in interactive mode, typing "/" will prompt for input. The input is
expected to be a simple text-pattern (case-insensitive) that will be compared
against the command name (using strcasestr). Entering "/", followed by "enter"
will clear the previous match (i.e., display all processes).

When top(1) is called from command-line, the -g flag can be used to provide
a filter pattern on invocation.

Fixed a small nit in the man page for interactive d usage.

[bcr]

OK from manpages.

[xtouqh_icloud.com]

usr.bin/top/machine.c

740

!= NULL

usr.bin/top/top.1

253

You can replace \*(lqd1\*(rq with .Dq d1.

259

260

[rew]

fix missing != NULL check

also other suggestions by xtouqh

[rew]

usr.bin/top/machine.c

740

ahh, thanks!

usr.bin/top/top.1

253

I kept with the lq/rq flavor to maintain consistency with the rest of the man page, but using the .Dq macro here is probably the better way to go.