[BuildLibrary] eliminate BuiltLibrary and BuiltOverlayLibrary

examples/tutorial/README.md

@@ -22,7 +22,7 @@ Contents
 - [library](library.py)
     * Continue from `devices.py` by declaring a mixed library with `BuildLibrary`
     * Import source-backed GDS cells and register python-generated recipes together
-    * Call `build()` to produce a normal library for downstream `Pather` usage and writing
+    * Call `build()` to produce a normal library and report for downstream `Pather` usage and writing
     * Explore alternate ways of specifying a pattern for `.plug()` and `.place()`
 - [pather](pather.py)
     * Use `Pather` to route individual wires and wire bundles

examples/tutorial/library.py

@@ -81,8 +81,9 @@ def main() -> None:
     # Build the declaration set into a normal library.
     #
 
-    built = builder.build()
+    built, report = builder.build()
     print('Built library contains:\n' + pformat(list(built.keys())))
+    print('Build dependency graph:\n' + pformat(report.dependency_graph))
 
     #
     # Continue designing against the built library.