Add autoenv reload subcommand

The `autoenv reload` subcommand reloads the current environment.

autoenv/_autoenv

@@ -16,6 +16,7 @@ _autoenv() {
         init:'add .enter and .exit scripts in current directory'
         edit:'edit .enter and .exit scripts in current directory'
         deinit:'remove .enter and .exit scripts in current directory'
+        reload:'reload the current environment'
         add=py:'add Python virtualenv to the autoenv'
       )
       _describe -t commands command commands && ret=0 ;;

autoenv/autoenv.zsh

@@ -12,7 +12,7 @@ autoenv() {
   case "$cmd" in
     -h|--help)  # Display help.
       echo "\
-usage: autoenv [-h] {init,edit,deinit}
+usage: autoenv [-h] {init,edit,deinit,reload,add=py}
 
 options:
         -h, --help  show this help message and exit
@@ -21,6 +21,7 @@ commands:
         init        add .enter and .exit scripts in current directory
         edit        edit .enter and .exit scripts in current directory
         deinit      remove .enter and .exit scripts in current directory
+        reload      reload the current environment
         add=py      add Python virtualenv to the autoenv"
       ;;
 
@@ -81,6 +82,16 @@ commands:
       done
       ;;
 
+    reload)  # Reload the current environment
+      if ! [ -f $PWD/.enter ] || ! [ -f $PWD/.exit ]; then
+        echo '.enter or .exit not found'; return 1
+      fi
+      # Exit the autoenv before editing.
+      _autoenv_exit $PWD
+      # Enter the autoenv.
+      _autoenv_enter $PWD
+      ;;
+
     add=py)  # Add Python virtualenv to the sandbox
       if ! [ -f $PWD/.enter ] || ! [ -f $PWD/.exit ]; then
         echo '.enter or .exit not found'; return 1