usability and cross browser compat for completer - dissmiss the completer, append what alredy type, **Plus** one caracter in some cases List of special caracter that are handle are in a given list `()[]./\-+` for the moment. usefull for exaple when typing : >>> np.s<tab>in( and not having to type '(' twice. they are handle separately has the [a-zA-Z] ones because otherwise they will screw up the regexp, and are opt-in to avoid bugs with invisible caracters send because some browser have 'keypress' event for meta keys close #1080 Note to this commit : list of test for the completer across browser with --pylab=inline flag #test direct one completion plt.an<tab> -> plt.annotate #test filter,tab, only one completion plt.a<tab>n<tab> -> plt.annotate # test partial common beggining # test dismmised if user erase plt.a<tab>nn<backspace><backspace>u<tab> -> completer to `aut` ........................................<tab><tab><tab> -> nothing should append .......................................................<backspace><backspace<backspace> -> completer cancelled #test dismiss if no more completion plt.s<tab>c -> completer 3 choices ...........u -> dismissed whith what user have typed. `plt.scu` # test dismiss in no completion, special symbol # opt-in list of caracters +-/\()[]. np<tab>.s -> a 'dot' sould dismiss the completer and be appended .........<tab>in( -> np.sin( np.s<tab>in[ -> np.sin[