Merge branch '2023-04-06-assorted-updates'

- Make use of the semi-formal "fallthrough" mechanism, update env tools
  to use /run for lockfile, add 2048 game (as a way to test console
  changes), update some CONFIG option logic in Kconfig, have lmb command
  show regions in use, remove some duplicate serial code, add
  __gnu_thumb1_case_si code and fix m68k custodian email address.