Remove command duration plugin and make it a theme feature

bash_it.sh

@@ -74,6 +74,9 @@ if [[ ! -z "${BASH_IT_THEME}" ]]; then
   BASH_IT_LOG_PREFIX="themes: p4helpers: "
   # shellcheck source=./themes/p4helpers.theme.bash
   source "${BASH_IT}/themes/p4helpers.theme.bash"
+  BASH_IT_LOG_PREFIX="themes: command_duration: "
+  # shellcheck source=./themes/command_duration.theme.bash
+  source "${BASH_IT}/themes/command_duration.theme.bash"
   BASH_IT_LOG_PREFIX="themes: base: "
   # shellcheck source=./themes/base.theme.bash
   source "${BASH_IT}/themes/base.theme.bash"

themes/command_duration.theme.bash

@@ -1,5 +1,8 @@
-cite about-plugin
-about-plugin 'keep track of the moment when the last command started, to be able to compute its duration'
+#!/usr/bin/env bash
+
+if [ -z "$BASHIT_COMMAND_DURATION" ] || [ "$BASHIT_COMMAND_DURATION" != true ]; then
+    return
+fi
 
 # Define tmp dir and file
 COMMAND_DURATION_TMPDIR="${TMPDIR:-/tmp}"