Disable setting title in emacs terminal (not supported)

This fixes #188 and takes place of #190, at least for now.

pure.zsh

@@ -85,6 +85,9 @@ prompt_pure_check_git_arrows() {
 }
 
 prompt_pure_set_title() {
+	# emacs terminal does not support settings the title
+	(( ${+EMACS} )) && return
+
 	# tell the terminal we are setting the title
 	print -n '\e]0;'
 	# show hostname if connected through ssh