Debug dottime in modeline

My modeline was displaying the local time (not UTC time) and appending the UTC
timezone offset, which was confusing me.

When it was `00:03` in London, my modeline would read `00:03+01`. One way of
interpreting this is that it's `00:03` in London and the `+01` is a reminder
that I'm one hour ahead of UTC. However, I was reading it as though it was
`00:03` UTC and thus `01:03` in London.

I had to set `display-time-string-forms` instead of `display-time-string` to
pass the `t` argument to the `ZONE` parameter to indicate that I'd prefer to use
UTC time and not local time when expanding the variables.

emacs/.emacs.d/wpc/wpc-misc.el

@@ -33,10 +33,11 @@
 ;; LON: +00 (UTC) or +01 (BST)
 ;; NYC: -05
 ;; SF:  -07
-(setq display-time-format
-      (concat "%H·%M"
-              (format "%0+3d" (/ (car (current-time-zone)) 3600))
-              " %a %d %b"))
+(setq display-time-string-forms
+      '((format-time-string
+         (concat "%H·%M"
+                 (format "%0+3d" (/ (car (current-time-zone)) 3600))
+                 " %a %d %b") nil t)))
 (display-time-mode 1)
 
 ;; Remove the boilerplate in the *scratch* buffer