implement tmux completion for CLIENTS AND SESSIONS

Fully implement all tmux commands found in the tmux man
page section titled: "CLIENTS AND SESSIONS"

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
implement tmux KEY BINDINGS

implement the commands in the KEY BINDINGS man page section

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
fix some of the initial parameters

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
move front flags to the top of the tmux file

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
tmux: don't suggest dirs

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
tmux: implement completion for panes

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
change spaces to tabs

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
tmux: add support for ENVIRONMENT

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
tmux: implement Status Line

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
tmux: use status-left short flags

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>