themes: use `_save-and-reload-history()`

First pass to use _Bash It_'s automatic history management.

themes/codeword/codeword.theme.bash

@@ -1,3 +1,5 @@
+# shellcheck shell=bash
+
 SCM_THEME_PROMPT_PREFIX=${SCM_THEME_PROMPT_SUFFIX}
 SCM_THEME_PROMPT_DIRTY="${bold_red} ✗${normal}"
 SCM_THEME_PROMPT_CLEAN="${bold_green} ✓${normal}"
@@ -19,11 +21,5 @@ prompt() {
   PS1="$(user_host_path_prompt)$(virtualenv_prompt)$(scm_prompt) $(mark_prompt) "
 }
 
-share_history() {
-  history -a
-  history -c
-  history -r
-}
-
-safe_append_prompt_command share_history
+safe_append_prompt_command '_save-and-reload-history 1'
 safe_append_prompt_command prompt

themes/doubletime/doubletime.theme.bash

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
 
 SCM_THEME_PROMPT_DIRTY=''
 SCM_THEME_PROMPT_CLEAN=''
@@ -30,9 +30,7 @@ fi
 
 function prompt_setter() {
   # Save history
-  history -a
-  history -c
-  history -r
+  _save-and-reload-history 1
   PS1="
 $(clock_prompt) $(scm_char) [${THEME_PROMPT_HOST_COLOR}\u@${THEME_PROMPT_HOST}$reset_color] $(virtualenv_prompt)$(ruby_version_prompt)\w
 $(scm_prompt)$reset_color $ "

themes/doubletime_multiline/doubletime_multiline.theme.bash

@@ -1,12 +1,10 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
 
 source "$BASH_IT/themes/doubletime/doubletime.theme.bash"
 
 function prompt_setter() {
   # Save history
-  history -a
-  history -c
-  history -r
+  _save-and-reload-history 1
   PS1="
 $(clock_prompt) $(scm_char) [$THEME_PROMPT_HOST_COLOR\u@${THEME_PROMPT_HOST}$reset_color] $(virtualenv_prompt)$(ruby_version_prompt)
 \w

themes/doubletime_multiline_pyonly/doubletime_multiline_pyonly.theme.bash

@@ -1,12 +1,10 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
 
 source "$BASH_IT/themes/doubletime/doubletime.theme.bash"
 
 function prompt_setter() {
   # Save history
-  history -a
-  history -c
-  history -r
+  _save-and-reload-history 1
   PS1="
 $(clock_prompt) $(scm_char) [$THEME_PROMPT_HOST_COLOR\u@${THEME_PROMPT_HOST}$reset_color] $(virtualenv_prompt)
 \w

themes/nwinkler/nwinkler.theme.bash

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
 
 # Two line prompt showing the following information:
 # (time) SCM [username@hostname] pwd (SCM branch SCM status)
@@ -29,9 +29,7 @@ prompt_setter() {
     else PROMPT_END=$PROMPT_END_DIRTY
   fi
   # Save history
-  history -a
-  history -c
-  history -r
+  _save-and-reload-history 1
   PS1="($(clock_prompt)) $(scm_char) [${blue}\u${reset_color}@${green}\H${reset_color}] ${yellow}\w${reset_color}$(scm_prompt_info) ${reset_color}\n$(prompt_end) "
   PS2='> '
   PS4='+ '

themes/nwinkler_random_colors/nwinkler_random_colors.theme.bash

@@ -1,4 +1,4 @@
-#!/bin/bash
+# shellcheck shell=bash
 
 # Two line prompt showing the following information:
 # (time) SCM [username@hostname] pwd (SCM branch SCM status)
@@ -96,9 +96,7 @@ prompt_setter() {
     else PROMPT_END=$PROMPT_END_DIRTY
   fi
   # Save history
-  history -a
-  history -c
-  history -r
+  _save-and-reload-history 1
   PS1="($(clock_prompt)${reset_color}) $(scm_char) [${USERNAME_COLOR}\u${reset_color}@${HOSTNAME_COLOR}\H${reset_color}] ${PATH_COLOR}\w${reset_color}$(scm_prompt_info) ${reset_color}\n$(prompt_end) "
   PS2='> '
   PS4='+ '

themes/pete/pete.theme.bash

@@ -1,10 +1,8 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
 
 prompt_setter() {
   # Save history
-  history -a
-  history -c
-  history -r
+  _save-and-reload-history 1
   PS1="($(clock_prompt)) $(scm_char) [$blue\u$reset_color@$green\H$reset_color] $yellow\w${reset_color}$(scm_prompt_info)$(ruby_version_prompt) $reset_color "
   PS2='> '
   PS4='+ '

themes/rainbowbrite/rainbowbrite.theme.bash

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
 
 # based off of n0qorg
 # looks like, if you're in a git repo:
@@ -7,9 +7,7 @@
 
 prompt_setter() {
   # Save history
-  history -a
-  history -c
-  history -r
+  _save-and-reload-history 1
   # displays user@server in purple
   # PS1="$red$(scm_char) $purple\u@\h$reset_color:$blue\w$yellow$(scm_prompt_info)$(ruby_version_prompt) $black\$$reset_color "
   # no user@server