Commit 57 (Beta Candidate)

Many small bug fixes and improvements, as well as the following specific
fixes and improvements:

Bug fixes:
  https://github.com/BorisMoore/jsviews/issues/270
  https://github.com/BorisMoore/jsviews/issues/271
  https://github.com/BorisMoore/jsviews/pull/275
  https://github.com/BorisMoore/jsrender/issues/241

Improvements:
  - ~tag.parents or ~parentTags now includes the current tag
  - template.link(container, data, context) now supports linking without
    passing in data - e.g. for a template that links only to context or
    helpers, not to a model.
  - Structured path dependencies for tags: For compiled templates or
    data-link expression, fn.paths and fn.deps now track dependencies
    separately for each argument or property of the tag.
  - Bug fixes and improvements to filtering support on observe APIs
  - Improvements and bug fixes and unit tests within support for
    top-level data-linking $.link(expression, target, data, context)
    or $.link(true, target, data, context).
  - Fixes to $.view(container, true) for array view when array is empty.
  - data-link="... onerror=null" is now equivalent to
    data-link="... onerror=''".