PropageteDescDomain applies the domain name from the "domain" attribute
of parent node (desc node) to the desc_signature node.  The structure
has longly generated by ObjectDescription.  But it must not be a new
rule.

This allows to build document that contains non standard doctree.

Unknown node error for pending_xref_condition is raised if an extension
that does not support the node installs a missing-reference handler.

The imgconverter unexpectedly goes to convert even if the given image
is supported by the target builder when the image globbing is not used.
This enables format guess-ing on not globbed.

Add test objects so all builders gets exposed to the new nodes.
Make the fallback node post-transform change desc_inline as well.
Make the html4, latex, and text writers handle desc_inline.