Disable ECB

I'm still not please with how this works.  There are features I would
like, but the implementation is awkward to me, at least in its
default state.
Disable Info+ frame fitting

I don't like my main frame changing sizes and locations when I open Info
or switch nodes.
Add gtags and helm-gtags to site-lisp

Previously the configuration relied upon optionally finding gtags.el in
/usr/share/gtags.  Now both it and helm-gtags are in
~/.emacs.d/site-lisp and my configuration has been update to delay load
gtags via `use-package'.  The helm-gtags setup and some of the bindings
were borrowed from jwiegley.