- Delete wren_io.c, wren_io.h, and io.wren source files
- Remove multi-arity print overloads and IO.read/IO.time methods
- Add System class with print, printAll, write, writeAll methods to core.wren
- Update all documentation examples and README to use System.print instead of IO.print
The addEntry function was incorrectly skipping tombstone entries when inserting new keys, causing the map to fill up with tombstones and eventually deadlock on insert. The fix removes the tombstone check that prevented overwriting tombstone slots with new entries, allowing proper reuse of removed entries.
A regression test (test/core/map/churn.wren) was added to verify that inserting and removing entries in a loop correctly maintains the map count without deadlocking.
