Fix multi-repl buffer handling

nrepl-connection-dispatch is now bound in nrepl-net-process-input, and
nrepl-emit-interactive-output uses nrepl-current-nrepl-buffer rather than
nrepl-current-connection-buffer.
Fix remaining checkdoc errors.
Add TravisCI build status image to the README
Merge pull request #264 from bbatsov/add-travis-icon

Add TravisCI build status image to the README
Add unit tests to travis configuration

This adds a top level Makefile with test, checkdoc and build targets
Fixes for compilation-error-regexp-alist

- Makes matching of filenames of the form (foo.clj:XX) in stacktraces
  more accurate (avoiding some spurious highlighting in compilation
  buffers).

- Uses a more idiomatic entry for `compilation-error-alist`, namely a
  symbol which points to `compilation-error-regex-alist-alist`.

- Moves the code adding entries to the former variables to the
  top-level, instead of calling it over and over everytime a repl is
  started.
Use wget to retrieve checkdoc-batch.el

curl was blocking on this download when run on travis.
Fix #261 - remove error overlay in nrepl-load-file

Previously the errors were cleared only if you used
`nrepl-load-current-buffer`.
Don't try to highlight a compilation error in a REPL buffer

Since the stacktraces from the REPL have no usable line numbers
we should not attempt to highlight compilation errors at all when
an error originated from the REPL.
Mention `nrepl-jack-in` and `nrepl` keybindings in the CHANGELOG
Don't suppress namespaces in macroexpansion

Suppressing namespaces makes it impossible to recursively expand in-place in the
macroexpansion buffer, in the case your macro calls are namespace qualified.
Merge pull request #263 from hugoduncan/feature/fix-multi-buffers

Fix multi-repl buffer handling
Merge pull request #265 from jaor/compile-regexps

Fixes for compilation-error-regexp-alist
Merge pull request #266 from hugoduncan/feature/add-unit-test

Adds the ert tests to the travis configuration
Merge pull request #267 from bbatsov/fix-261

Fix #261 - remove error overlay in nrepl-load-file
Merge pull request #268 from bbatsov/improve-error-hl

Don't try to highlight a compilation error in a REPL buffer
Merge pull request #269 from bbatsov/update-changelog

Mention `nrepl-jack-in` and `nrepl` keybindings in the CHANGELOG
Merge pull request #270 from hugoduncan/feature/show-namespaces-in-macroexpansion

Don't suppress namespaces in macroexpansion
Add an event buffer for debugging

Use nrepl-log-events to control logging.
Address review comments