Adding the ability to specify tmux session name.

Change-Id: Iee7f34de4448e9ab5d383e6e2eb871639271fdb5

modules/tmux/README.md

@@ -23,6 +23,10 @@ following line to *zpreztorc*:
 In both cases, it will create a background session named _prezto_ if the tmux
 server is not started.
 
+You can change the default session name with:
+
+    zstyle ':prezto:module:tmux' session 'YOUR DEFAULT SESSION NAME'
+
 With `auto-start` enabled, you may want to control how multiple sessions are
 managed. The `destroy-unattached` option of tmux controls if the unattached
 sessions must be kept alive, making sessions available for later use, configured

modules/tmux/init.zsh

@@ -31,10 +31,10 @@ if [[ -z "$TMUX" && -z "$EMACS" && -z "$VIM" ]] && ( \
 
   # Create a 'prezto' session if no session has been defined in tmux.conf.
   if ! tmux has-session 2> /dev/null; then
-    tmux_session='prezto'
+    zstyle -s ':prezto:module:tmux' session 'session' || session='prezto'
     tmux \
-      new-session -d -s "$tmux_session" \; \
-      set-option -t "$tmux_session" destroy-unattached off &> /dev/null
+      new-session -d -s "$session" \; \
+      set-option -t "$session" destroy-unattached off &> /dev/null
   fi
 
   # Attach to the 'prezto' session or to the last session used.