Make implicitly global parameter declarations local

These parameters were not explictly marked as local, which causes zsh to
make them global by default. This is presumably unintended, and pollutes
the environment, so they have been explicitly made local in the manner
already present in the file.

These parameters were found using the zsh option WARN_CREATE_GLOBAL.
There may be other implicit global parameters present, as it only
displays a warning when the relevant code is evaluated.

zsh-vi-mode.zsh

@@ -402,7 +402,7 @@ function zvm_find_bindkey_widget() {
   local keymap=$1
   local keys=$2
   local prefix_mode=${3:-false}
-  retval=()
+  local retval=()
 
   if $prefix_mode; then
     local pos=0
@@ -422,6 +422,7 @@ function zvm_find_bindkey_widget() {
 
     local result=$(bindkey -M ${keymap} -p "$prefix_keys")$'\n'
 
+    local i=
     # Split string to array by newline
     for ((i=$spos;i<$#result;i++)); do
 
@@ -529,6 +530,7 @@ function zvm_readkeys() {
     if [[ "${keys}" == $'\e' ]]; then
       timeout=$ZVM_ESCAPE_KEYTIMEOUT
       # Check if there is any one custom escape sequence
+      local i=
       for ((i=1; i<=${#result[@]}; i=i+2)); do
         if [[ "${result[$i]}" =~ '^\^\[\[?[A-Z0-9]*~?\^\[' ]]; then
           timeout=$ZVM_KEYTIMEOUT
@@ -557,6 +559,7 @@ function zvm_readkeys() {
     zvm_exit_oppend_mode
   fi
 
+  local retval=()
   if [[ -z "$key" ]]; then
     retval=(${keys} $widget)
   else
@@ -619,7 +622,7 @@ function zvm_string_to_hex() {
 
 # Escape non-printed characters
 function zvm_escape_non_printed_characters() {
-  local str=
+  local i= str=
   for ((i=0;i<$#1;i++)); do
     local c=${1:$i:1}
     if [[ "$c" < ' ' ]]; then
@@ -2729,6 +2732,7 @@ function zvm_highlight() {
       local raw=true
       local spl=(${(@s/ /)region_highlight[i]})
       local pat="${spl[1]} ${spl[2]}"
+      local j=
       for ((j=1; j<=${#ZVM_REGION_HIGHLIGHT[@]}; j++)); do
         if [[ "$pat" == "${ZVM_REGION_HIGHLIGHT[j]:0:$#pat}" ]]; then
           raw=false
@@ -3360,6 +3364,7 @@ function zvm_init() {
   esac
 
   # Bind and overwrite original y/d/c of vicmd
+  local c=
   for c in {y,d,c}; do
     zvm_bindkey vicmd "$c" $default_handler_widget
   done
@@ -3369,6 +3374,7 @@ function zvm_init() {
   local surrounds=()
 
   # Append brackets
+  local s=
   for s in ${(s..)^:-'()[]{}<>'}; do
     surrounds+=($s)
   done