wldbg: start implementing interactive mode

Make interactive mode register its pass and spawn the client. For now,
it has simple (read none) parsing of arguments. Later getopts will be
used.

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
wldbg: wrap invoking passes into function

no comment
dump: add dump pass

I use it a while now but forgot to add it to the git.

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
wldbg: handle signals

Handle interrupt signal and SIGCHLD.
wldbg: add missing new line
wldbg: add one-by-one mode

In this mode, wldbg reads connection and split incoming data
into messages. Each message is then processed and resend separately.

User cannot turn it on now (no arg switch for that), but this
is on TODO list.

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
wldbg: add running flag

This flag is set to one, when epoll loop can run. If it is set
to 0, then the wldbg will go out of the loop end exit.

This is used from sighandler, instead of calling exit() - it was leaky.

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
wldbg: add -s option

This optoin turns on one-by-one mode. It's kind of code duplication,
but for now it's OK. Later I'll use getopt.