Some addition for scala-mode

Hi all,

I have added some extension for scala-mode. Please see attached patch.

1. Made scala-run-scala command pop up *inferior-scala* buffer if the
comint process is runnning.
2. Added C-c C-z to keymap that enables us to show *inferior-scala*
buffer
quickly (run-lisp flavor).

Regards,
Tomohiro

Index: emacs/scala-mode-ui.el
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