With the addition of the boards manager, and the new architecture for managing core files for the Zero, I'm confused by how to tell what's changed and where. For example, when 1.6.6 was released, did I need to also go into the boards manager and update core files, or were core file changes included in the 1.6.6 download? Are core file changes documented in the build release notes, or do I need to look elsewhere for these kinds of changes. How about changes made to libraries for compatibility with the Zero. Where are these documented? Also, if I keep around the old 1.6.5 release (to tests for regressions), does the boards manager update the core files used by this older version? If so, how can I check for regressions in libraries, core files and one IDE? Is this new architecture for file management documented anyplace?