history-substring-search: bind arrows in both emacs and viins modes

This avoids an ordering dependency between this and the vi-mode plugin.

plugins/history-substring-search/history-substring-search.plugin.zsh

@@ -13,11 +13,14 @@ fi
 
 
 # Bind terminal-specific up and down keys
-
+# Bind in both emacs and vi modes so it works in both, and is not
+# sensitive to whether this is loaded before or after the vi-mode plugin
 if [[ -n "$terminfo[kcuu1]" ]]; then
-  bindkey "$terminfo[kcuu1]" history-substring-search-up
+  bindkey -M emacs "$terminfo[kcuu1]" history-substring-search-up
+  bindkey -M viins "$terminfo[kcuu1]" history-substring-search-up
 fi
 if [[ -n "$terminfo[kcud1]" ]]; then
-  bindkey "$terminfo[kcud1]" history-substring-search-down
+  bindkey -M emacs "$terminfo[kcud1]" history-substring-search-down
+  bindkey -M viins "$terminfo[kcud1]" history-substring-search-down
 fi
 

plugins/history-substring-search/update-from-upstream.zsh

@@ -76,10 +76,12 @@ cat >> $plugin_basename.plugin.zsh <<EOF
 # Bind terminal-specific up and down keys
 
 if [[ -n "\$terminfo[kcuu1]" ]]; then
-  bindkey "\$terminfo[kcuu1]" history-substring-search-up
+  bindkey -M emacs "\$terminfo[kcuu1]" history-substring-search-up
+  bindkey -M viins "\$terminfo[kcuu1]" history-substring-search-up
 fi
 if [[ -n "\$terminfo[kcud1]" ]]; then
-  bindkey "\$terminfo[kcud1]" history-substring-search-down
+  bindkey -M emacs "\$terminfo[kcud1]" history-substring-search-down
+  bindkey -M viins "\$terminfo[kcud1]" history-substring-search-down
 fi
 
 EOF