.gitconfig: Explicitly disable `indent-with-non-tab`

Don’t use `indent-with-non-tab`. This config flag is PERNICIOUS. If turned on, Git won’t tell you that you indented your code incorrectly. Instead, when it is pushing your changes to your remote repo, Git will silently convert any consecutive 8-space strings it sees into tab characters. This can be highly undesirable, especially if you collaborate with a team that expects the code to be indented using spaces instead of tabs.

At the very least, the comment above this line should very clearly explain the fact that `indent-with-non-tab` does more than advertised in the `git-config man page (https://www.kernel.org/pub/software/scm/git/docs/git-config.html).

Closes #351.
.osx: Add missing value

In order to properly overwrite the `key` of a `domain`, `defaults` needs to be provided with a valid `value` for the `key`:

    `defaults write <domain> <key> <value>`

Closes #350.
.cask: Add Opera, Opera Developer and Opera Next

Closes #348.
.osx: Allow installing Chrome user scripts via GitHub Gist or Userscripts.org
.osx: Change minimize/maximize window effect

By default, OS X Mavericks uses the annoying `genie` effect whenever windows are minimized/maximized. This commit changes that preference and makes OS X use the more tolerable `scale` effect.

Closes #355. Ref. #270.
.osx: Remove “disable opening and closing window animations”

Sadly, this doesn’t work anymore in OS X 10.9.

Closes #270.
.osx: Comment computer name settings

It’s good to have these commands here as a reference, but it’s annoying when running `.osx` on multiple computers in the same network.
.exports: Explicitly use UTF-8 even for `LANG`
.osx: Add ExpandedStateFor* variants for OS X 10.9

Closes #361.
.aliases: Use `en0` for `localip`
.osx: Update iOS Simulator symlink
Install casks via Caskfile

`brew bundle` can now be used for casks as well.

Closes #365.
Brewfile: Install GNU `sed`
Brewfile: Install some more useful tools
.functions: Make `gi` accept any number of arguments

Closes #367.