Remove unused modes

Rm nyan-mode, ibuffer-git, scratch
Use zenburn-theme
Remove custom eshell prompt color
Remove custom highlight-indentation-mode colors
Use again exec-path-from-shell-initialize
Remove some diminish usages
Use cider instead of nrepl.el and simplify config
Remove some key-chord bindings
Move multiple-cursors's temp file to tmp
Add tramp sudo filter-group
Conditionally turn on pandoc-mode
Turn on yas-minot-mode in lua-mode