Add an event buffer for debugging

Use nrepl-log-events to control logging.
Address review comments
Ensure sent message id is logged
Close nrepl-event-buffer-name on nrepl-quit

Also calls nrepl-close-ancilliary-buffers on nrepl-quit, which was missing.
Introduce the option to hide special buffers

Some "boring" buffers can now optionally be hidden by
the users via the use of the `nrepl-hide-special-buffers` setting.
By default all special buffers are visible.
Fix nrepl-hide-special-buffers docstring.
Fix test names.
Keybinding improvements

* Bound `nrepl-interrupt` to `C-c C-c` in REPL buffers, to respect Emacs comint tradition.
* Bound `nrepl-load-current-buffer` to `C-c C-c` to respect the common practice to use this keybinding for
a very popular action. Arguably in nrepl nothing is as popular as loading the current buffer.
* `nrepl-switch-to-repl-buffer` now accepts a prefix argument. If one is passed it will take into account the
namespace of the current Clojure source file.
Fixed a typo.
Rebind `C-c C-c` to nrepl-eval-expression-at-point.
Merge pull request #255 from bbatsov/hide-bufffers

Introduce the option to hide special buffers
Improve compilation error handling

To avoid delays associated with retrieval of the stacktrace, highlighting is
based on the exception message that is reported by the stderr-handler in
nrepl-load-file-handler.  The exception trace is put in the *nrepl-error*
buffer, but not displayed by default.

Adds an nrepl-visit-error-buffer function, to visit *nrepl-error*.

Installs nrepl-jump-to-compilation-error as the next-error-function in
nrepl-interaction-mode buffers, to jump to the compilation error using
next-error.

Adds an optional eval-error-handler to nrepl-make-response-handler.

Adds nrepl-popup-on-error, to control whether stacktraces (globally) are popped
up by default.
Fix build failures due to 3eaa49b5

Fixes the doc strings to pass checkdoc.
Merge pull request #277 from hugoduncan/feature/fix-build-failures

Fix build failures due to 3eaa49b5
Merge pull request #272 from hugoduncan/feature/improve-load-file-on-errors

Improve compilation error handling
Merge pull request #273 from bbatsov/keybindings

Keybinding improvements
Merge #281: Clean up killed connections.
Merge #275 - colorize output sent to nrepl buffer.