IntelliJ添加Emacs编辑器

Intellij只支持emacs as a external tool：

https://www.jetbrains.com/help/idea/2016.2/tutorial-using-emacs-as-an-external-editor.html

对Vim支持很好，是不是要跳Vim坑了

https://www.jetbrains.com/help/idea/2016.2/tutorial-using-intellij-idea-as-the-vim-editor.html