docs: remove pages invalidated by opc refactor
docs: document hyperlink feature analysis
acpt: add hyperlink feature
text: add _Run.hyperlink
oxml: add CT_Hyperlink
text: add _Hyperlink.address getter
text: add _Hyperlink.address setter
sld: add parent protocol and .part property

Child objects of Slide need to know their parent so they can pass up
delegation requests for things they need but can't know, like the
package part they belong to.
opc: add Part.relate_to(is_external) support
opc: add RelColl.get_or_add_ext_rel()
opc: add Part.target_ref()
acpt: add remove hyperlink scenario
text: add _remove_hlinkClick()

Also implements "change hyperlink", setting a new URL when one already
exists.

along the way:

* relocate _get and _set_bool_attr into standard sort order
opc: organize Part methods and tests by interface

no code changes
opc: add Part.drop_rel()
opc: refactor RelColl._rel to dict
opc: refactor RelColl to subclass dict
opc: factor _element up to Part

.blob() for XML parts goes with it
acpt: add hyperlink in table cell scenario
tbl: add _parent.part to table elements

Along the way:

* Resequence Table.height() in lexical order, no code change