Custom pluggable analyzers

[jackfirth]

Resyntax should provide a customizable, modular API for defining whole-module analysis passes to provide nonlocal information to refactoring rules. Parts of this are implemented but there's a lot of additional work to do, including exposing the analyzer definition API, exposing the syntax path and syntax property entry APIs, exposing the analyzer testing framework, allowing rules and suites to declare what analyzers they need, documentation for all of the above, and general polishing.