Add support for arbitrary data in template tags

Where data is defined under a `data` field in 'loconfig.json'.

Example:

```json5
{
    "paths": {…},
    "data": {
        "foo": "b"
    },
    "tasks": {
        "concats": [
            {
                "includes": [
                    "{% paths.scripts.src %}/vendors/*.js"
                ],
                "outfile": "{% paths.scripts.dest %}/a{% foo %}c.js"
            }
        ]
    }
}
```

build/helpers/config.js

@@ -18,6 +18,10 @@ try {
     // do nothing
 }
 
+loconfig.data  = (loconfig.data ?? {});
+loconfig.paths = (loconfig.paths ?? {});
+loconfig.tasks = (loconfig.tasks ?? {});
+
 export default loconfig;
 
 export {

build/helpers/template.js

@@ -9,7 +9,8 @@ import {
 } from '../utils/index.js';
 
 const templateData = flatten({
-    paths: loconfig.paths
+    ...loconfig.data,
+    paths: loconfig.paths,
 });
 
 /**