Add a site template to the pybble.ext.page blueprint
Pass the object into the template engine if we'd like to render one.
Templates: "match=parent" adds the template to whatever owns it
Render an object directly, not as_dict
Make DEBUG_WEB truly three-valued

* web debugger
* pdb
* default error page
ext.page test: show the site
add: be more verbose
pybble obj get/list: also show references to the object
Fix the "site template" test
Use '==', not 'is', for object comparison
replace a couple of "A is (not) B" comparisons with == / !=