.curlrc: Disguise as IE 9 on Windows 7

This matches the `.wgetrc` settings.
.aliases: Add `timer`

`timer` can be used as a stopwatch.

Hat tip: https://twitter.com/tow8ie/status/360077953238962176
.gitconfig: Improve display of astral Unicode symbols in diffs

Thanks to @holman for the tip: https://speakerdeck.com/holman/more-git-and-github-secrets?slide=38
.osx: Add GPGMail 2 settings

http://support.gpgtools.org/kb/faq-gpgmail/gpgmail-2-hidden-settings
.osx: Disable the sound effects on boot
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  .osx: Disable the sound effects on boot
  .osx: Add GPGMail 2 settings
  .gitconfig: Improve display of astral Unicode symbols in diffs
  .aliases: Add `timer`
  .curlrc: Disguise as IE 9 on Windows 7