Improve ag tab completion

* Remove unnecessary `uniq`
* Look for tags in tmp/tags or .git/tags
* Send errors to /dev/null if the file(s) do not exist

See http://tbaggery.com/2011/08/08/effortless-ctags-with-git.html for an
explanation behind the reasoning for .git/tags.
Add vim-multiple-cursors plugin for Vim
Revert "Add vim-multiple-cursors plugin for Vim"

This reverts commit 422a6f6d3324a7c6060793657054025d41a7bab3.

Want to go through a PR cycle.
\unset QUIET is case sensitive
Introduce ~/.zsh/configs

Just before loading `~/.zshrc.local`, load:

1. `~/.zsh/configs/pre/**/*`
2. `~/.zsh/configs/**/*` # excluding pre and post
3. `~/.zsh/configs/post/**/*`

About the zsh glob:

- `.`: only produce normal files.
- `-`: follow symlinks to their final file; skip any broken links.
- `N`: do not complain about zero matches.

Big ups to Pat Brisbin for finding `N`.
Introduces `git_template` for init templating

Inspired by http://tbaggery.com/2011/08/08/effortless-ctags-with-git.html

* Make `ctags` executable configurable
* Adds `git ctags`
* Runs `ctag` on `commit` / `branch` / `checkout`
* Extensible via `~/.git_template.local/hooks/{pre,post}-*`
* explain `git_template` under `git` section
Add vim-repeat plugin

Repeat.vim remaps `.` in a way that plugins can tap into it. With this
plugin you can, for instance, repeat commands from surround.vim.
Merge remote-tracking branch 'upstream/master'