Fix -s for st and xst

Fixes #29.

README.org

@@ -172,7 +172,7 @@ These terminals have been tested with tdrop and support the =-s= and =-a= flags
 - Sakura
 - Roxterm
 - Tilix (previously terminix)
-- st (-s does not work)
+- st/xst
 - Alacritty
 - xiate
 - [[https://github.com/kovidgoyal/kitty][kitty]]

tdrop

@@ -570,7 +570,8 @@ program_start() {
 			tmuxifier load-session $session_name || \
 			tmuxinator start $session_name || \
 			tmux new-session -s $session_name'"
-		if [[ $program =~ ^(urxvt|alacritty|xiatec$) ]]; then
+		# note: st will work with or without the -e flag (like kitty)
+		if [[ $program =~ ^(urxvt|alacritty|xiatec|st$) ]]; then
 			program_command="$program_command -e bash -c $tmux_command"
 		elif [[ $program == kitty ]]; then
 			program_command="$program_command bash -c $tmux_command"