Fix edit-command-line binding

This binding doesn't work when the edit-command-line.zsh file is loaded
after the key-bindings.zsh file because 'bindkey -e' in key-bindings.zsh
resets the binding. Moving the bindings to they key-bindings.zsh file
and removing edit-command-line.zsh.

lib/edit-command-line.zsh

-autoload -U edit-command-line
-zle -N edit-command-line
-bindkey '\C-x\C-e' edit-command-line

lib/key-bindings.zsh

@@ -26,6 +26,11 @@ bindkey "^[[3~" delete-char
 bindkey "^[3;5~" delete-char
 bindkey "\e[3~" delete-char
 
+# Edit the current command line in $EDITOR
+autoload -U edit-command-line
+zle -N edit-command-line
+bindkey '\C-x\C-e' edit-command-line
+
 # consider emacs keybindings:
 
 #bindkey -e  ## emacs key bindings