How to uninstall a module that has added a basefield that has data

Defining new anchors is tricky and basically impossible without looking at the PGF code used to define the shape. But aliasing anchors is quite straightforward (once you have the command to do it):

\documentclass[tikz,border=5]{standalone}
\usetikzlibrary{shapes.geometric}
\makeatletter
\def\pgfaliasanchor#1#2#3{%
  \expandafter\gdef\csname pgf@anchor@#1@#2\endcsname{%
    \pgf@sh@reanchor{\csname pgf@sh@ns@\pgfreferencednodename\endcsname}{#3}%
  }%
}%
\makeatother

\pgfaliasanchor{regular polygon}{peter}{90}
\pgfaliasanchor{regular polygon}{paul}{330}
\pgfaliasanchor{regular polygon}{mary}{south west}
\begin{document}
\begin{tikzpicture}
\node [fill=gray!50, regular polygon, minimum size=1.5in] (shape) at (2,2) {};
\foreach \anchor in {peter, paul, mary}
  \draw [draw=red] (shape.\anchor) 
    circle [radius=1/20] node [above] {\tt\anchor};
\end{tikzpicture}
\end{document}

If you use F.lux

F.lux has a known issue (see seventh bullet point) of display flickering on El Captian. You can fix it by turning off your Mac's Automatically Adjust Brightness feature.

To turn off Automatically Adjust Brightness, go to System Preferences -> Display.

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If you don't use F.lux

Your issue sounds like a bug in OS X. It may be fixed in Sierra, but if you don't want to try out the beta first, you can easily stop it from happening by switching to F.lux:

1. Delete the Warm Colors profile (or any other display profiles you have set up in System Preferences -> Display -> Color)
2. Download F.lux and follow the setup to get your ideal screen warmth (if you want your screen to turn warmer at night).
3. Set up F.lux to turn on automatically at your desired time or just turn off that functionality and turn it on/off manually.

Running this command without SSH keys should prompt you for a password. I am using something similar and don't have any problems.

Most probably you are having problems connecting to the ssh server. Make sure

1. You have access to the server. You can run traceroute your.server.ip.address to see if you can connect to it.
2. Make sure you have the ssh server up and running on port 22 - it might run on different port, or down. Try ssh -v [email protected] to see if you can even connect.
3. userfoo might not have permissions to connect trough ssh, if you have another user, you can test with it.

Edit

It appears in one of the comments you are using PuTTY - which usually is not a problem but it reveals that you are trying to execute this from a Windows machine. Unfortunately this command will not work as you are piping to your PC, and that means the client need to have dd installed. This part - dd of=/home/user/image.gz is actually executed on your PC, not on the server.

That would be your problem if you manage to connect to the server. You should be able to log in trough ssh to the server, and it seems that is not the situation.

I have tested the IP you posted here ending with 11.26 and there is no response on port 22 from the SSH server. You need first to fix that.