installing and configuring emacs

Emacs modes

name	instruction	description	type
`follow-mode`	split a frame to two vertical windows that show the same buffer by `C`-`x` `3`, then `M`-`x` `follow-mode`	edit parts of a long file that are vertically far apart	editing
`shell`	`M`-`x` `shell`	run a shell through an Emacs buffer	software
`whitespace-mode`	`M`-`x` `whitespace-mode`	display various kinds of whitespace characters	viewing
`markdown-mode`	`M`-`x` `markdown-mode`	for viewing and editting files using markdown markup language	viewing, editting
`yasnippet`	enter different mode, e.g. `xml-mode`, `lisp-mode`, etc., start typing the beginning of code snippets, and press `Tab` to autocomplete the rest	for quickly entering code snippets in different modes	editting

`company`	Modular text completion framework.	viewing, editting
`flycheck`	On-the-fly syntax checking.	editting
`helm`	Helm is an Emacs incremental and narrowing framework.	?
`use-package`	A use-package declaration for simplifying your .emacs.	configuration
`which-key`	Display available keybindings in popup.	UI
`yasnippet`	Yet another snippet extension for Emacs.	Editting