Minor bugfixes & PHP 8.1 compatibility

fix: bind multiple attribute placeholders #327

Example: <a href="/path/to/{{project}}/with/{{another}}/attribute/placeholder"> - any attribute can now contain multiple placeholders.

290 default placeholder #328

Example:

Hello, {{name ?? you}}!

fix: resolve deprecation notices #329

PHP 9 will introduce a lot more strict typing, and 8.1 has started emitting deprecation notices. These have all been addressed in this release.

fix: insert template before correct element #330

When template elements have more than one similar siblings, the correct next sibling is remembered, and the template element is inserted in the correct position.

Identify template parents when there are ambiguous XPath selectors #337

Similarly to above, when two or more template elements have similarly-addressed parents, the template element is now always added to the correct one.