.gitconfig: Add a `glog` alias (log --graph --oneline --decorate)

I use this a bunch, so save some typing with an alias.  The output is
especially pretty now that it's automatically colored (thanks,
color.ui!).
.config/rss2email.cfg: Change python-pep to python-checkins

I want to get the changes as well as the commit messages (which can
occasionaly be cryptic).  On peps@python.org, Barry Warsaw suggested:

On Sun, Oct 21, 2012 at 04:22:28PM -0400, Barry Warsaw wrote:
> On Oct 20, 2012, at 10:53 AM, W. Trevor King wrote:
> >I'm interested in following a few packaging PEPs, but not
> >interested enough to subscribe to python@ and python-dev@.
>
> Maybe as an alternative you can follow the checkins list by Gmane.
> You'll get everything committed to all the Python repos, but it
> shouldn't be too difficult to hunt down the PEP checkins.
>
> http://dir.gmane.org/gmane.comp.python.cvs

Finally change my rss2email configuration over to use his suggestion.
.gitconfig: Add --topo-order to glog alias

This makes it easier to mentally separate development in concurrent
feature branches.
.config/rss2email.cfg: Add `sendmail` (default value)

New configuration option since f01eac2 (email: Make path to sendmail
configurable, 2013-02-15).
.config/rss2email.cfg: Add wireless-patches feed

Following linux-wireless' SubmittingPatches documentation.
.config/rss2email.cfg: Add some Gentoo-oriented feeds

gentoo-universe is a superset of planet-gentoo.  I'll probably get
tired of the volume and drop gentoo-universe soon ;), but I'll start
off watching both.
.config/rss2email.cfg: Add greg-kh feed

Discovered via a post on planet Gentoo.
.bashrc.d/20nobeep: Style and POSIX cleanups

* `which` is not in POSIX 2008, use `command -v` instead.
* Avoid the temporary XSET variable.
* Reorganize to consolidate if statements.