Merge pull request #546 from tuhdo/master

Add discover-my-major
Fix define-key 'help-command
Merge pull request #551 from toctan/fix-define-key

Fix define-key 'help-command
Extend improvements section
Remove EmacsWiki section
Leftover from previous commit
Log nREPL messages by default
Get rid of the deprecated clojure-test-mode
Add extra keybindings for eval-defun and eval-buffer
Don't recompile elc files outside of Prelude