Simplify `omf cd` code

This also namespace the function to `omf.packages`.

pkg/omf/cli/omf.cd.fish

-# SYNOPSIS
-#   Change the current working directory to plugin / theme home directory.
-#
-# OPTIONS
-#   <name> Name of the package or theme.
-
-function omf.cd -a name -d "Change the current working directory to plugin / theme home directory."
-  if test -z $name
-    pushd $OMF_PATH
-    return 0
-  end
-
-  if test -e $OMF_CONFIG/pkg/$name
-    pushd $OMF_CONFIG/pkg/$name
-  else if test -e $OMF_CONFIG/themes/$name
-    pushd $OMF_CONFIG/themes/$name
-  else if test -e $OMF_PATH/pkg/$name
-    pushd $OMF_PATH/pkg/$name
-  else if test -e $OMF_PATH/themes/$name
-    pushd $OMF_PATH/themes/$name
-  else
-    echo (omf::err)"$name is not a valid package/theme name"(omf::off) 1^&2
-    return $OMF_INVALID_ARG
-  end
-end

pkg/omf/cli/omf.packages.cd.fish

+# SYNOPSIS
+#   Change the current working directory to plugin / theme home directory.
+#
+# OPTIONS
+#   <name> Name of the package or theme.
+
+function omf.packages.cd -a name -d "Change the current working directory to plugin / theme home directory."
+  if test -z "$name"
+    pushd $OMF_PATH
+    return 0
+  end
+
+  for path in {$OMF_CONFIG,$OMF_PATH}/{pkg,themes}/$name
+    if test -e "$path"
+      pushd $path
+      return 0
+    end
+  end
+
+  echo (omf::err)"$name is not a valid package/theme name"(omf::off) 1^&2
+  return $OMF_INVALID_ARG
+end

pkg/omf/omf.fish

@@ -55,9 +55,9 @@ function omf -d "Oh My Fish"
     case "c" "cd"
       switch (count $argv)
         case 1
-          omf.cd
+          omf.packages.cd
         case 2
-          omf.cd $argv[2]
+          omf.packages.cd $argv[2]
         case "*"
           echo (omf::err)"Invalid number of arguments"(omf::off) 1^&2
           echo "Usage: $_ "(omf::em)"$argv[1]"(omf::off)" <name>" 1^&2