templater/new: call fromVarying in context of binder.

* don't make me regret this.
model/new: implement issues and validation for models and attributes.
list/bug: do not replace list instance on #removeAll().
list>filtered/noop: use safer remove; use new Varying#reactNow().
list>catted/bug: was ignoring initial elems; not calculating idx.
Make util.toString work in more browsers
varying/bug: should also unlisten on child varying on plain value.
package/new: actually export issue object.
Merge pull request #2 from progman32/master

Make util.toString work in more browsers
Merge remote-tracking branch 'origin/master' into with-extract

Conflicts:
	lib/collection/filtered-list.js
	lib/collection/list.js
	lib/core/varying.js