Support shared, device-specific i3 configurations

Separated i3/configuration since some of my devices support XFree86 keysyms
while others do not. This introduced some cascading changes.

- Removed ~/.config/i3/config from this repo. Since I will be switching between
  devices semi-regularly and that file will be generated each time I switch to a
  different device running an X session, I don't want the i3/config to spam my
  `gst` and `gd` when I haven't changed configuration in either config.shared or
  config.device.
- Update aliases, variables, etc. to point to config.shared instead of the
  generated file.
- Ensure that X sessions generate the i3/config file.
- Ensure that i3 reload and restart command generate the i3/config file.

configs/shared/emacs/.emacs.d/wpc/packages/wpc-keybindings.el

@@ -70,7 +70,7 @@
     "ef" (lambda () (interactive) (wpc/find-file-split "~/functions.zsh"))
     "el" (lambda () (interactive) (wpc/find-file-split "~/variables.zsh"))
     "ex" (lambda () (interactive) (wpc/find-file-split "~/.Xresources"))
-    "ei" (lambda () (interactive) (wpc/find-file-split "~/.config/i3/config"))
+    "ei" (lambda () (interactive) (wpc/find-file-split "~/.config/i3/config.shared"))
     "em" (lambda () (interactive) (wpc/find-file-split "~/.tmux.conf"))
 
     "B"  #'magit-blame

configs/shared/emacs/.emacs.d/wpc/packages/wpc-misc.el

@@ -59,7 +59,7 @@
 (set-register ?f '(file . "~/functions.zsh"))
 (set-register ?l '(file . "~/variables.zsh"))
 (set-register ?x '(file . "~/.Xresources"))
-(set-register ?i '(file . "~/.config/i3/config"))
+(set-register ?i '(file . "~/.config/i3/config.shared"))
 (set-register ?m '(file . "~/.tmux.conf"))
 
 (set-register ?p `(file . ,wpc/current-project))