This file contains a list of changes that can/must be done when
we break API/ABI for 3.x.


- Move PIKA_REPEAT_TRUNCATE to the start of the enum and rename it
  to NONE. Rename the current NONE to EXTEND or something.

- Add LOTS of padding to all public class structs.

- Have private pointers in all public instance structs, not just
  GET_PRIVATE() macros, in order to inspect the private structs
  easily in the debugger.

- Remove compat values from all enums.

- Add user_data to all functions passed to pika_widgets_init()

- Preferably make pika_widgets_init() take a vtable with padding.

- Change pika_prop_foo_new() to use the nick as label, or find some
  other way to use the nick.

- Pass the plug-in protocol version on the plug-in command line.