Fix issue No.35 : prompt for kill buffer with client will hang emacs

When the indirect buffer is create from a buffer with clients, kill it
will show prompt to confirm, that will hang emacs.
So I need to remove clients before kill buffer, which will prevent
the prompt to show.
Fix issue #34: recursive call ace jump make view mess up

The ace jump session do not allow to be created recursively, but
this indeed happened when you trigger ace jump hot key again while
you already start one session. So we stop the previous one if a new
one want to start.