runonce

USAGE: runonce -c atom -e 'atom foo.txt' -s 'atom foo.txt'
    -s server command
    -c wm class
    -e client command

if class not provided, deduce class by provided command
if window matching class exists:
    switch to window
else:
    if server command is provided:
        execute server command
    if client command is provided:
        execute client command

if only class is provided, just switch to window
if only client command is provided, switch and execute
if  nly server command is provided, switch or execute
if both client and server provided, {switch and execute client} or execute server