[input] fix prompt after <Tab><Tab><Ctrl-C>

The issue is fixed by adding `zle redisplay` after `zle
expand-and-complete` for the expand-and-complete key binding. An
additional `print -n '...'` is also included to show an indicator while
the menu is loading, and that is purely cosmetic.

There's still one glitch: the prompt jumps one line up after
<Tab><Tab><Ctrl-C>. This was observed in Prezto too.

Fixes #85, closes #89

modules/input/init.zsh

@@ -102,6 +102,15 @@ if [[ -n "${key_info[BackTab]}" ]]; then
   bindkey "${key_info[BackTab]}" reverse-menu-complete
 fi
 
+# Redisplay after completing, and avoid blank prompt after <Tab><Tab><Ctrl-C>
+expand-or-complete-with-redisplay() {
+  print -n '...'
+  zle expand-or-complete
+  zle redisplay
+}
+zle -N expand-or-complete-with-redisplay
+bindkey "${key_info[Control]}I" expand-or-complete-with-redisplay
+
 # Put into application mode and validate ${terminfo}
 zle-line-init() {
   if (( ${+terminfo[smkx]} )); then