tmux: do not auto-load tmux inside of Emacs/Vim

When Emacs and Vim are launched from outside of an interactive shell,
$TMUX and $STY are not set; check for Emacs and Vim environment
variables instead.

plugins/tmux/tmux.plugin.zsh

@@ -80,7 +80,7 @@ compdef _tmux _zsh_tmux_plugin_run
 alias tmux=_zsh_tmux_plugin_run
 
 # Autostart if not already in tmux and enabled.
-if [[ -z "$TMUX" && "$ZSH_TMUX_AUTOSTART" == "true" ]]; then
+if [[ -z "$TMUX" && "$ZSH_TMUX_AUTOSTART" == "true" && -z "$INSIDE_EMACS" && -z "$EMACS" && -z "$VIM" ]]; then
   # Actually don't autostart if we already did and multiple autostarts are disabled.
   if [[ "$ZSH_TMUX_AUTOSTART_ONCE" == "false" || "$ZSH_TMUX_AUTOSTARTED" != "true" ]]; then
     export ZSH_TMUX_AUTOSTARTED=true