.mutt/muttrc: Reverse sort between threads by most recent message therein.

* Lessens chances of missing a message in a very old thread.
* Increases incentive to delete or archive messages.
.zshrc: t: Roland's alias for incessant use of cat.
.zshrc: ClearClipboard: Clean up xclip processes.
.zshrc: StableQueue: Open Linux kernel stable queue in a browser.
.zshrc: Move portable options out of per-shell case, and vice-versa.
.zshrc: readline Ctrl-R (incremental history search) emulation in Vi insert mode.
.vimrc: CtrlP: Enable extensions of interest.
.pystartup.py: History file support.
.pystartup.py: Colourize prompt.
.pystartup.py: Enable rudimentary auto completion.
.pystartup.py: Spawn editor on \e in console.
.pystartup.py: [Heretical] switch-case class.

Don't use this for anything but the sake of expediency in one-off, quick
hacks.
.pystartup.py: Colourize tracebacks.

Not very useful right now due to lack of differentiating colouring on
key elements of traceback.
.pystartup.py: Crude object pretty-printing.
.zshrc: Set pager preferences.

* Pass through raw chars (e.g. SGR—colour).
* Exit and don't reset term if output under a page
* Break lines
.zshrc: python: Silence start up.
.zshrc: ModPaths: Remove redundant grep use.
.bashrc: PS1: More robust rendering.
.zshrc: URL quoting conveniences.
.zshrc: vlc: Start without decorations by default.