Generic link tracking and refactoring support for macros

Macros should be able to report that they contain links to other Confluence pages, which would then be tracked via the links table.

During refactoring, the page should be rendered in "refactor mode", which instructs macros to rename any links they might contain. This is a little tricky because of the interaction between renderer and macro (and having the macro locate itself in the page and edit itself successfully), but it shouldn't be too hard.