vim: Improve command-line completion

Turn on wildmenu (Default in neovim).
Let vim first complete the longest common string between matches before
seleting full matches. (Similar to completion done by bash or zsh)

.config/vim/vimrc

@@ -49,6 +49,14 @@ endif
 set copyindent
 " Show ruler at 80 and 100 columns
 set colorcolumn=80,100
+" Show menu for possible matches when using command-line completing.
+if (has('wildmenu'))
+	set wildmenu
+endif
+" Command-line completion tab behavior:
+" First:  Complete longest common string and show wildmenu
+" Second: Complete each full match (Cycle through the menu)
+set wildmode=longest:full,full
 
 " Keybindings ##################################################################
 " Set leader key