Add bash-it restart command

Also add completion and completion tests

lib/helpers.bash

@@ -45,7 +45,7 @@ alias reload_plugins="$(_make_reload_alias plugin plugins)"
 bash-it ()
 {
     about 'Bash-it help and maintenance'
-    param '1: verb [one of: help | show | enable | disable | migrate | update | search | version | reload | doctor ] '
+    param '1: verb [one of: help | show | enable | disable | migrate | update | search | version | reload | restart | doctor ] '
     param '2: component type [one of: alias(es) | completion(s) | plugin(s) ] or search term(s)'
     param '3: specific component [optional]'
     example '$ bash-it show plugins'
@@ -57,6 +57,7 @@ bash-it ()
     example '$ bash-it search [-|@]term1 [-|@]term2 ... [ -e/--enable ] [ -d/--disable ] [ -r/--refresh ] [ -c/--no-color ]'
     example '$ bash-it version'
     example '$ bash-it reload'
+    example '$ bash-it restart'
     example '$ bash-it doctor errors|warnings|all'
     typeset verb=${1:-}
     shift
@@ -84,6 +85,8 @@ bash-it ()
         func=_bash-it-migrate;;
       version)
         func=_bash-it-version;;
+      restart)
+        func=_bash-it-restart;;
       reload)
         func=_bash-it-reload;;
       *)
@@ -314,6 +317,23 @@ _bash-it-doctor-() {
   _bash-it-doctor-all
 }
 
+_bash-it-restart() {
+  _about 'restarts the shell in order to fully reload it'
+  _group 'lib'
+
+  saved_pwd=$(pwd)
+
+  case $OSTYPE in
+    darwin*)
+      init_file=.bash_profile
+      ;;
+    *)
+      init_file=.bashrc
+      ;;
+  esac
+  exec "${0/-/}" --rcfile <(echo "source \"$HOME/$init_file\"; cd \"$saved_pwd\"")
+}
+
 _bash-it-reload() {
   _about 'reloads a profile file'
   _group 'lib'