Add fields to asset map.
Prefer dot notation for property access.

Prefer dot notation -- x.a rather than [x a] -- for two reasons:

1) It's slightly shorter than square-bracket notation.

2) The compiler produces a diagnostic when dot notation is used to
access a property not available in the static type of the object
reference; this may help catch errors earlier.
Add +[ZJXMLUtil child:of:].
Add convenience wrapper for XML elements.
Parse chunks and assets.