Do not load interactive parts when not required (#34)

install

@@ -183,6 +183,8 @@ __fsel() {
   echo
 }
 
+if [[ $- =~ i ]]; then
+
 if [ -n "$TMUX_PANE" -a ${FZF_TMUX:-1} -ne 0 -a ${LINES:-40} -gt 15 ]; then
   fzf-file-widget() {
     local height
@@ -220,6 +222,7 @@ fzf-history-widget() {
 zle     -N   fzf-history-widget
 bindkey '^R' fzf-history-widget
 
+fi
 EOFZF
     fi
   fi