- reset scheduler savestate to what it was for years before rewind
-- changing saved variables should be done after thorough testing. right now, adding some vars breaks some machines, adding other vars breaks others
- switch to megabyte-wise capacity
-- savestate size greatly differs between machines, relying on state count is unstable
- switch to internal indexing
-- no longer depends on inaccurate machine time
- rewind accelerator key in debugger (Ctrl+F11)
- report capacity hit (once), with some useful info
- make error reports saner
- mention rewind and rewind_capacity in the docs
